I'm still surprised by Fallon. His show is lively, funny and fresh enough (hey, it's late night ... even the best are recycling bits Steve Allen did 50 years ago). I didn't think this show would amount to much of anything, and I really believe it's one of the best out there.
Note: Jon Stewart and Stephen Colbert -- very, very funny guys with terrific shows -- aren't really doing "late night TV" and therefore aren't being considered here. Still, if you add them, that makes for four hours of decent programming per night. Nothing to shake a stick at.