When I read this thread I just couldn't resist to post a few things on the Belgae. Just for fun and a bit of insight on these tribes.
It may be interesting for people to read. (I hope I don't post something that's been written before here.)

My sources are:

the book "De oude Belgen" (=the old Belgians) written by Ugo Janssens, 2007
this may or may not have an English translation.

The collections and info from the Gallo-Roman museum in Tongeren, Belgium.

I'll start with writing a list (the Latin names) on the various tribes described in the book with a bit of extra info on them:

-Ambiani: lived in their main town Samarobriva (=Somme-bridge) (some total war vets recall that name?), at the River Somme.
57 BC joined the Belgian alliance opposing julius ceasar. After a defeat they allied with the Romans 54BC. Helped Vercingetorix in 52 BC by sending 5000 men in the fight for Alesia.
51BC they fought one last time against the Romans with the Bellovaci. They are supposed to be the first coinforgers since 200BC.

-Atrebates "those who posess villages" : Their territory was nowadays Artois. In 200 BC some famillies immigrated to southernwest England in nowadays Sussex, Hampshire, Berkshire.
In 57 BC they assaulted the captial of the Remi, Bibrax (Bibracte). The same year they also fought with the Nervi and Viromandui against ceasar's troopsnear the Selle river. After a lost battle Ceasar apointed a capable warlord Commios as their king.They went on campaign in England on Roman request. In 52 BC Commios turned from the Romans and joined Vercingetorix after the loss at Alesia he rebelled in 51BC, but eventually had to flee to England where he became king of the 'British' atrebates.

-Atuatuci: Of germanic origin living between the Rhine and Maas. According to ceasar descendants of the Teutons and Kimbren. In 57BC they arrived too late on a battle which possibly had cost a Belgian victory, they fell back and broke a pact with the Romans, after their failed attempt to surprise the Romans to still try and turn the loss to a victory, Ceasar made a example of them by enslaving 53 000 men, women and children. The Eburones payed homage to themuntill after that defeat. In 54 BC they joined a raid with the Eburones(led by one of the Eburon kings Ambiorix), to assault a Roman wintercamp which at that time ended in a stalemate.

-Baetasii: Little is known of this tribe, they were recorded by Plinius the elder when he served in the Roman army as an officer.

-Bellovaci 'Roaring fighters': Lived on the right side of the Oise-river. It's suggested they lived in the city Bratuspantium(Bratosporios).
They were a big and mighty tribe, in 57BC they send 60 000 men to join the Belgian coalition at this time there was distrrust between them and the Remi and Suessionen due to alliances with the Romans. In 52 BC they refused to send Vercingetorix any men, because they wished to beat the Romans on their own in a seperate war.

-Brittani: Litlle is known about them except that they were of celtic origin and lived near the Rhine, they are suspected to be a remnant of their tribe that went to England.

-Caeroesi: Of german origin their name is suspected to mean "herders of sheep", though there is debate on this. In 57 BC they send 40 000 men to fight the Romans along with the Eburons and Condrusi, all of these are considered of germanic origin, Ceasar called them 'germani cisrhehani' Germans on the left side of the Rhine. Sources tell they lived close to nowadays city Luik towards the border of Germany.

-Caleti "Tough men" : They answered to the Bellovaci, fighting alongside them, Caesar named them in his list of enemy tribes.

-Catuslogi: Should've lived near nowadays Normandy, Plinius the Elder mentioned them. Their name is supposed to mean "fighting troops".

-Catuvellauni "Leaders in battle" : In 40 BC they won territories from the atrebates in England, only in 50 BC the Romans conquered them, they lived north of Theems.

-Condrusi: They are suspected to come from the place Condroz, they crossed the Rhine and joined the Gallic rebellion in 57BC and 52 BC. They were supposed to be vassals of the Treveri.

-Coritani: One century before the Roman invasion they crossed the channel. They founded Leicester, and controlled Nottinghamshire, Lincolshire and part of Yorkshire, they became a powerfull tribe and are considered to be the first to forge coins in England.

-Eburones: Of germanic origin. They were vassals of the treveri and payed loans to the atuatuci.
They lived in the region of the province Limburg in Belgium. There is debate on their name it's meaning possible it could be 'People of the taxus" or "people of the boar".
A popular tribe in nowadays Belgium due to the story of their king Ambiorix who in 54 BC tricked the Roman commanders Sabinus and Cotta into an ambush where 7000 Roman soldiers commanders included died. Caesar drove the Eburones from their lands and gave it to a befriended tribe the Tungri.

Menapii: Of celtic origin. This tribe was never fully conquered by the Romans, partly due to the rough terrain where they lived, they were considered to be a collection of seperate communities living on small islands near the Rhine and Maas all up to the sea. They were sailors who traded with their 'Brittish' cousins. They joined all the great revolts and along with the Morini they fought against ceasar in 55BC with bloody losses and victories in equal measure.

Morini "Sea people": They were sailors aswell whom traded with the peoples in south England. They lived between the north sea and the Ijzer river.
Their most important port was Portius Itius or nowadays Boonen/Boulogne-Sur-Mer. Their capital was Taruenna or nowThérouanne/Terwaan.
In 57 BC they joined the Belgian coalitien with 25 000 men. 2 years later they made a pact with the Menapii and the tribes from Armorica (north of France).
After a defeat they fell under the rule of Commios, who was befriended with Rome at that time. They send 5000 men to Vercingetorix in 52 BC.

-Grudii: Litlle is known except that they lived close to the Samber river and were vassals of the Nervii.

-Nervii: One of the most powerfull tribes of the Belgae, several subtribes were ceutroni, Grudii, Lavaci, Pleumoxii and Geudummes, they joined all the great battles against the Romans.
In 57 BC, under command of their king Boduognat they brought the Romans to the brink of destruction along with the atrebates a,d viromandui.
In 54 BC they supported the Eburon kings(!) Ambiorix and catuvolcos in their battle against the Romans who camped there for winter.
They also supported Vercingetorix in 52 BC.

-Paemani: Of germanic origin, they joined the first big Belgian coalition against Caesar, they were vassals of the Treveri.

- Remi "The first" "The princes" "The eldest": This powerfull tribe never fought against the Romans. When the Roman invasion began they immediately requested an alliance.
Their capitol Bibrax (Bibracte). They were close with the suessiones. They never fought against the Romans to keep their favourable trade with England.

-Segni: Their lands were between the Treveri, Eburones and condrusi. In 57 BC they joined the Belgian coalition, though being a small tribe they feared the Romans and to be in their favor, snitched Eburones whom where in hiding on their territory between 53BC and 51 BC.

-Silvanectes: Litlle is known of their existance, they are suspected to be close kin of the Suessiones.

-Sunuci: They were the last germanic groups during the Roman invasion to cross the Rhine. Plinius the Elder made note of them, they were supposed to live close the the province of Limburg in Belgium.

- Suessiones: Their capital was Noviodunon "New fort" nowadays Soisson. There's debate on their name's meaning possible are "Those who posses much food", "those who fortify their homeland" or
"Those who posses six armies". Their laws were near identical with those of the Remi. Under command of their king Galba they joined with 50 000 men in the first coalition against Caesar. After this they would become allies of the Romans (just like the Remi). in 51 BC ceasar send 4 legions to scare away the atrebates and Bellovaci who wanted to invade Suessone territory.

- Treveri "Those who travel past" : A powerfull tribe, were of germanic origin, but with a celtic culture, their territory was nowadays luxembourg and a part of Germany. They are supposed to have had the best Belgian cavalry. They were a divided people Cingetorix leading the pro-Rome clans and Undutiomaros the rebels.
The atuatuci payed tribute to them.

-Trinovantes: This tribe who became most powerfull settled in nowadays Essex and controlled a part of Suffolk.
Their main territory was north/ east Londen, they were conquered by the Romans in the year 43.

-Tungri: They got the territory of the Eburones after they were largely driven from their lands.
Their capital is assumed to be nowadays Tongeren.

-Veliocassi "The best in battle": They lived in nowadays Normandy. In 57 BC they send 10 000 men to join the fight against the Romans in 52BC they supported Vercingetorix and in 51BC formed a coaltion with the Atrebates, Ambiani, Caleti and Bellovaci.

-Viromandui "Those who crush others" : Supposed to live in the area called Vermandois and near the Somme river. They had close ties with the suessiones. In 57BC they joined the big and several smaller coalitions against the Romans.

This kinda decribes a few tribes of the Belgae during Ceasar's invasion of Gaul on their political stances, their heritage etc.
Hope you enjoy the read and as caesar himself said "Of all Gauls the Belgians are the bravest!" hope they atleast get a bit attention in EBII.

I'll write more now and then.