In person (usually concerns my roommates and classmates, whom I see in person most often)
Text messages (often to set up an in-person meeting for purposes of business or leisure, or to have small conversations when I'm away from the computer)
Telephone conversation (for something that's short but urgent)
#eoff (to talk to you fine folks)
Facebook, LJ, email, etc
AIM (on fairly rare occasions actually. mostly to discuss homework with my classmates.)