Well, the list is quite long, and I'm bound to forget them, but I will go with I can think of right now, but if there are any that aren't listed and you want to know, just ask.
Accents:
Soft English, 'Eavy English, Irish, Scottish, French, Spanish, Italian, German, Russian, Arabic, Indian, Jamaican, Canadian (Wisconsin...?), African, Mexican, and others.
Regional/other Accents:
Snobbish Rich Man, New Yorker, United States Jew, Wisconsin, Southern, Redneck, Hillbilly, Valley-girl (hehehe... about that), Surfer/stoner/hippy, Effeminite southern man, "flaming" homosexual, "slow" englishman, Explorer Englishman, New York Italian Mobster, New York Italian Mob Boss A (the fat ones), New York Italian Mob Boss B (the raspy ones), Idiot, Angry Italian in New York, Heavily Lisping Nerd, Heavy smoker old woman, Old woman, Old man, VERY old man, Suspiciously Masculine woman, Pirate, Southern Baptist Preacher, Woman From the Hood.
Animated/movie/Video game Character Impersonations:
Fred Fredburger, Stewie Griffin, The Oiled up Deaf Guy, Kool-Aid Man, Mr. Bottomtooth, Peter Griffin, Ollie Williams, Lois Griffin (not a typo), Eric Cartman, Kenny McCormick, Mr. Macky, Mr. Garrison, Mr. Slave, Nathan Explosion, William Murderface, Toki Wartooth, Swiskgarr Skwigelf, Pickles the Drummer, Meatwad, Gaara of the Sand, Lloyd Asplund; aka The Earl of Pudding, Bartz Klauser, Exdeath, Warrior of Light, Garland, Captain Jack Sparrow, Patrick Star, Pinky, Brain, Goofy, Mickey Mouse, Smeagle/Gollum.
Actor/TV Personality Impersonations:
Sean Connery, Arnold Schwarzenegger, Grant George, Antonio Banderas, Mr. T, Macho Man Randy Savage, Jerry Sienfeld, Dave Chappelle, Chris Tucker, Ray Romano, Christopher Walken, Elvis Presley, George W. Bush, William Clinton, Simon Cowell, Michael Jackson, William Shatner...
Ask me about others some time, cuz I can't remember them all...