I still recall my Sicilian spy telling me that the Danes were going to invade me "the year after next" in the very year that they swarmed across about 4 borders!
Oh give him a break, he obviously meant to say "the year before the next"

I guess the reason I don't use agents much is because they take wayy too much annoying mousework. Seriously. Like that spy tactic without border forts like Caravel described, that would drive me insane moving your spies all the time like that. The other thing I don't like about them is that the results are often very ambiguous or unpredictable. The only thing I do use is bribing (love it, actually :P especially when the target is a Man Of Principle with Weak Principles ^^), and Priests/Alims just to look behind enemy lines (Priests/Alims because I'm building a Church/Mosque any place that has a Keep or better anyway), I have put a Priest in 60+ provinces but I'm not doing anything like that again. Oh and I try to marry all my princesses, just because I'm a nice guy and don't want them to spend their life in a nunnery.

I have never launched a single crusade either! I guess that's mostly because 90% of the time I'm excommunicated

What do Inquisitors do? Are they really that effective at killing generals? What effect does the "out-of-control" inquisition have? I might just try one out in the campaign I'm doing right now!