Here's the handy form to report evildoers:
https://my.barackobama.com/page/s/report-an-attack?source=em12_20120526_sc_tt'
Awhile back, someone here posted a huge list of actual reports (from Twitter, maybe?). Most were hilarious, like:
I want to report my next door neighbor. He looks just like Karl Rove.
I want to report my dog Duke. He barks angrily every time the President appears on TV.