As I've said before, Twitter is like THE most POINTLESS thing ever put on the internet: the basic premise of Twitter was already an existing feature on BOTH MySpace (now My[____]) AND Facebook.
Facebook I could never get the hang of... I tried it for a week and hated it: it's confusing, hard-to-navigate, hardly user-friendly, and you can't even customize your profile like you could MySpace... then MySpace went and Facebookified themselves since FB was creaming them, so I deleted my old MS account... and thanks to Sarge, I recently deleted my FB account that I never used anyway too.