I love Schoolhouse Rock! to this day. I have the boxed set of video tapes and have recently added the anniversary DVD to my Amazon wishlist. The Wikipedia entry [Schoolhouse Rock!] is really good (even better since I went in and added a few little improvements ;-)
I think my single favorite contributor to SchoolHouse Rock! is Lynn Ahrens (added a little to that entry too). Not surprisingly, she continues writing to this day. I love the songs she wrote for Schoolhouse Rock and her performances of them. Of her songs, I especially like Interjections; A Noun is a Person, Place or Thing; The Tale of Mr Morton; Interplanet Janet; Telegraph Line; A Victim of Gravity; No More Kings; Fireworks; and The Preamble - that is to say, most everything she wrote. Lynn didn't work on Multiplication Rock at all, which probably partially explains why that's my least favorite set. Ms Ahrens has a website detailing her work, including a place to listen to some of her songs .
Some of my other favorite songs are: Rufus Xavier Sarsaparilla; My Hero, Zero; and The Shot Heard Round the World. What are yours?