I've never physically stalked anyone, however I'm ashamed to admit that I've e-stalked a guy I had a crush on once. :/ I used to read his Facebook/MySpace all the time and added his MSN and used to talk to him on that sometimes but never actually spoke to him in person despite the fact he was in my class at school. I realised my crush on him wasn't going anywhere, so I eventually admitted to him what I thought of him, of course it didn't work out, though he was nice about it.
My SA stopped me going up to him and trying to get to know him, which is a shame, because I actually got along with most of his friends, I just didn't know any of them on a semi-personal basis.