Accents: Scottish, Irish, British, Cockney, Russian, French, German, Jamaican, Indian, Native American, Scandinavian, Southern, Bostonian, New Yorker
Character archetypes: old prospector, surfer, country lawyer, baptist preacher, mobster, mob boss, a million others
Character voices: ones I've actually performed are:
Rod & Nickie (Avenue Q)
Grimgnaw (Neverwinter Nights)
Legato Bluesummers (Trigun)
Elmo (Sesame Street)
King of Town, Homsar, Homestar (homestarrunner.com)
Dinobot, Waspinator (Beast Wars)
Yoda (Star Wars)
Gollum (Lord of the Rings)
Meatwad (Aqua Teen Hunger Force)
Kiff, Horrible Gelatinous Blob, The Giant Brain, Robot Santa (Futurama)
Vincent Price
Henry Kissinger
All characters (Yu-Gi-Oh: The Abridged Series)
I can usually, decently emulate a lot of character voices, I just have to try.