I'm a fan of the Robot Chicken intro if only because it is done by Les Claypool, but in a similar vein as the Kids in the Hall intro is the State intro.
I also love the Cowboy Bebop song and that alone is enough, but to have cool animated space sequences is just about the tops.
As for the futurama intro, it's good, but have you seen the intro scene to The Beast with a Billion Backs? It's frickin' brilliant! Just watch it, I'm sure they have it on yourtubes or bytetorrents or sommat of your newfangled downloady funzones. (I'd find a link but honestly I think youtube is total drek. Anyone of any worth should get their own page. OK, that's harsh, but damn I hate youtube.)
EDIT for pain:
First... Thank you for reminding me of the prisoner, it's been ages since I watched that. But I AM NOT A NUMBER!
Second, since someone HAD to throw in a scary anime intro, I submit to you the Intro to Excel Saga.