d0z.me: The Evil URL Shortener by Ben Schmidt, Spare Clock Cycles, 19-December-2010.
There are a few other little nasty uses of this type of Innocent Surfer background activity. DoS would seem the least profitable.
With these issues in mind, I began wondering: what would happen if I mashed them all together? Enter d0z.me: a proof-of-concept URL shortener that, while getting users to their destinations, also covertly attacks an arbitrary server.