As for SNL, the old-school cast was and still is the best. I love the Belushi skit EQ mentions, but the ones that most influenced my developing psyche were two sketches involving Jane Curtin interviewing Dan Ackroyd as Irwin Mainway, a purveyor of hideously unsafe children's toys like "Bag-O-Broken-Glass" and Halloween costumes like "Johnny Human Torch," which consisted of some oily rags and a match.
I also love an Ackroyd classic where he was in drag as Julia Child. Cutting a finger while slicing open a goose, he gushes fake blood like a super-soaker and valiantly tries to carry on, with the force of the sanguinary geyser blasting a half-dozen band-aids loose, before finally keeling over from blood loss, crying out "Don't forget to save the liver!!" with a last frenzied shout.
Phoebe, you get a cookie for mentioning The Upright Citizen's Brigade!
Very Python indeed! I still use the phrase "looking into the Bucket of Truth" when friends ask me for difficult advice. As a side note, in a Sci-Fi storyline that I hope to develop as either a comic book or role-playing game campaign some day, I was planning on naming a quartet of the villain's thugs Antoine, Colby, Trotter, & Adair and seeing who spotted the reference...
Incidentally, this is my 250th post.