Cartoon Network/Adult Swim - not nearly as much as I used to, but I still tune into a few shows here and there.
Teletoon - I don't even consider the alternatives for watching Ninja Turtles and The Batman, and they run Space Ghost!
Comedy Network/Comedy Central - fairly interchangable, but both are good. The Comedy Network gets the edge for running South Park with no noisy promos over the credits.
NBC/Global - grouped together because they both run My Name Is Earl and Heroes. I like 'em.
G4TechTV (Canada) - all the good aspects of G4 (X-Play, Attack of the Show), less of the crap... plus there's anime!
ColoursTV - 4 hour FUNimation Channel block, baby! Though I wish they'd show more episodes of Kodocha and Case Closed, already!
Toon Disney, Boomerang, Nicktoons Network - all more currently enjoyable than the networks that spawned them.
Space, Spike and G4 - because I like a good Star Trek episode now and then.
And I probably would be watching Razer and MuchMusic (strange choice for my tastes, but they run anime series Beck), I just don't currently subscribe to them.
I think if somebody could make me a cable package with just those channels, I wouldn't need anything else.