I am, ah, somewhat different in person. I met my current girlfriend on a mailing list. When we first met, she said "Wow, you a lot less articulate in person"
Hah. I might be the same way. A lot of times I realize I don't know how to pronounce words or that I've never said words verbally even though I use them all the time online.
Case in point: 'articulate'. I bet I've used it quite a bit online but nary a time in real life.