I'm a member of various writing lists, and I variously see writers get their head in a tizzy about piracy. Now we all agree piracy isn't the best thing, but there really isn't any way to do anything about it which doesn't cost more time, effort and money than you are recovering.
I won't go into a long rant on the topic; this blog is not the place for that. However, Joe Konrath has a nice (now old, but still relevant) post that addresses all the common complaints.
The short version is: deal with it, there is no evidence that piracy harms sales.
Read it here. Worthwhile. Now stop worrying about piracy and get back to writing: http://jakonrath.blogspot.com/2010/05/piracy-again.html