Death By Roo Roo is probably the best improv group in New York City right now. Neil Casey and John Gemberling are two of their best members (although picking your favorite DBRR cast member is like picking your favorite part of an orgasm).
It’s good to see improvisers getting wider attention, so I’m chipping in my two cents and linking to two very funny video starring these two guys:
Mr. Casey: http://www.todaysbigthing.com/2009/12/08
Mr. Gemberling: http://entertainment.todaysbigthing.com/2009/11/17