To stalk somebody over the internet by finding and reading many of their posts on a forum. Usually done by overly curious friends/family members or by admiring fans. It can easily be performed by entering someone's name, e-mail address or username (if it's unique to that person) into a search engine.
Creepy stalker: "You live in Birmingham, right?"
Stalkee: "Woah, how did you know that?"
Creepy stalker: "Oh, I was sorta post-stalking you lolz."
Stalkee: "Wtf. Get a life."