I know what you mean.

On the internet, and to an extent with some of my friends, I'm talkative, energetic, Monty Python quoting and generally "wierd".

Around most of my friends, I'd feel really wierd if I were like that, so I'm fairly quiet and "normal".

When I'm by myself I'm either mopey and lacking in the self-esteem department, (Don't ask me why.) or I'm the the "net me" only crazier, and inside joke-ier. My mind is not the place you'd want to get stuck in... ;)

Somehow, the multiple versions of me, come together. At least, they're not completely unco-operative...