Other than the standard facebook abuse whenever someone forgets to log off/lock their computer, not much. And I've stopped doing that, purely because I've run out of things to write. (when the same person leaves their computer on and leaves the house at least five times a day on a regular basis, there's only so many things you can write - I ended up asking /b/ for advice, before realising that that was a really bad idea. Especially if you inadvertently leave your own name in the screencap. Never again)
Oh, I have a friend who decided the 'yellow car' game was still funny, and would giggle inanely after getting us each time one went past. So a group of us found 3 or 4 yellow car owners, convinced them to follow us for a bit, and then exacted our yellow car revenge on said friend. 'Twas good.