I said I was going to do more Harry Potter nostalgia. Well, the fact that this post is Harry Potter related is nostalgic, I suppose, but mostly it's just your everyday putting characters from other media into Hogwarts Houses. :P
Here is my assessment. Feel free to add your own input. I tried to do this humorously, as opposed to doing it as Srs Bsns, although there's also analysis to it.
Parks and Recreation
Leslie: The Hat actually tinkers between Hufflepuff and Gryffindor. Leslie is driven by causes and doing the right thing, to be sure, but in the end it's her family and friends who come first - no matter what. She is also a hard worker. However, when the Hat is about to Sort her in Hufflepuff, Leslie immediately begins shouting (in her head) "GRYFFINDOR GRYFFINDOR GRYFFINDOR."
Ron: The Hat bounces a bit with Ron,; he's very self-serving, but it's part of a deeper philosophy, which seems very Ravenclaw. On the other hand, he rejects the concept of philosophy. In the end he's a Slytherin, but sometimes secretly wishes he'd been in Ravenclaw. Too many Ministry pleasing kiss asses in Slytherin for his liking.
Tom: Tom is Sorted into Slytherin and immediately tries to invent a new Sorting Hat that simply says "BALLIN' TIME" when one is Sorted. Other Slytherins are a little embarrassed of him.
April: Serpents? Sign her up for Slytherin. However, the Hat recognizes a certain creativity to April's weirdness, and she is dragged to Ravenclaw kicking and screaming.
Andy: Hufflepuff. He puts his friends and family first - no matter what. (Season 2 and onwards Andy.)
Ann: Hufflepuff for similar reasons.
Donna: Gryffindor.
Mad Men
Almost everyone: Slytherin. Have you watched that show?
Exceptions: Joan (Ravenclaw), Peggy (Hat takes a long time, then settles on Gryffindor), Stan (same), Ken (Ravenclaw).
30 Rock
Almost everyone: Slytherin. Again, have you watched that show?
Exceptions: Liz (the Hat goes back and forth between Ravenclaw and Gryffindor before settling on the latter), Criss (Hufflepuff because come on), Kenny (Gryffindor - we learn he's actually the Gryffindor).
Buffy the Vampire Slayer
Buffy: Just before Sorting, Buffy spots a vampire. She slays it, but not before some epic sarcasm... and almost misses the Sorting Ceremony altogether. The Hat barely lets her put it on before shouting "GRYFFINDOR!"
Willow: The Hat really wants Ravenclaw, but it realizes Willow's driven by the good fight. It also notes she is better off surrounded by common friends, than alone with a spellbook and candles. GRYFFINDOR.
Xander: Gryffindor.
Cordelia: Cordelia's like, so going to be in Slytherin. All of her family was. But to her surprise, she's Sorted into Gryffindor. She quickly makes use of it, but secretly wonders if the diversion makes her different, somehow.
Tara: Ravenclaw.
Oz: Ravenclaw. (Maybe Willow should've been in Ravenclaw after all.)
Giles: Ravenclaw. Teenage Giles wasn't into all that "fight the good fight" bollocks, but he was still smart.
(... also, Giles is the only character who technically could've gone to Hogwarts.)
Again, let me know who you would Sort, and where. Also, feel free to request any other fictional Sortings!