Everybody else has most of the obviously great/hilarious shows, so to the uncommon...
ok, I know most people are sick of irreverant, surreal 11 minute adult swim comedies, especially after so many poor showings, but I have to say
Metalocalypse and Frisky Dingo are the best quarter hour shows adult swim has had since ATHF and Sealab. Dare I say it, perhaps better?
Alright, brief synopsis for the unfamiliar
Metalocalypse: This show details the lives of metal band, cultural phenom, and world's 12th leading economy, Dethklok. They just passed Belgium. A shadowy illuminati group tries to spy on, infiltrate and control this "threat to the status quo", while the band themselves are so filthy rich and out of touch with everything that all they know is how to make brutal metal and how to negotiate a contract.
Frisky Dingo: this one is even better, haha. I don't really think it's *about* anything, even though there is a season long storyline. It's about billionairre Xander Crews, who is also the super-hero Awesome X, after he's cleaned up crime and his merchandise and job as Awesome X go down the shitter. He's essentially batman, only instead of batman pretending to be Bruce Wayne, he's Bruce Wayne pretending to be batman. Add in the delightful new villain on the block, Killface, and what do you have? Comic Jumbalaya, that's what.
as for real shows, it doesn't quite match up to most of hte real sitcoms you mentioned, but Sports Night was an awesome and way underrated show.