Wow, what a great question! I remember when I was a teenager my best friend and I had a discussion about this same topic. Are we going purely for quality or hard rocking, in your face tunes of the highest quality? Some great posts so far, Baba O'Riley is hard to top but this slew of gems just popped in my head and make it awfully hard to decide...

Song - Album - Artist (in no particular order)
Dirty Deeds Done Dirt Cheap - AC/DC - Dirty Deeds Done Dirt Cheap
Whole Lotta Love - Led Zeppelin II - Led Zeppelin
Black Dog - Led Zeppelin IV - Led Zeppelin
Immigrant Song - Led Zeppelin III - Led Zeppelin
Good Times Bad Times - Led Zeppelin I - Led Zeppelin
Roadhouse Blues - Morrison Hotel - The Doors
Sympathy for the Devil - Beggars Banquest - Rolling Stones
Start Me Up - Tattoo You - Rolling Stones
Message in a Bottle - Reggata de Blanc - The Police

Obviously most of the songs I listed are more 'in your face' type of tunes


PS, sorry BKS but 'Manic Depression' was the first track from 'Are You Experienced?', not 'Foxy Lady'.