I've put a 48-hour block on user Tim706, who has recently committed a series of vandalisms and has no history of productive edits. (In each case, his vandalism consists of replacing an existing photograph with a doctored photo on which he has drawn red horns and a beard and a caption that says, "Bitch ate my dog.")
This is the first time I've ever blocked a user. I did a quick scan of Wikipedia policies, and I think that a ban under these circumstances is within my authority as a sysop. If this is not the case, please correct me.
--Sheldon Rampton