Maybe you guys already know about this but while searching for a question I came across this site: www.systut.com
Looks like someone is extracting the questions. They do link back to SO though. Not sure if this is causing any real harm.
The content on SO is licensed CC wiki with attribution which means, in short, that anyone can use it as long as they post attribution (ie, a link back here is fine).
This was done intentionally to avoid CDDB, IMDB, and similar issues with "Users generate the content that we own and profit off of."
They are not following the attribution requirements (linked at the bottom of every page):
4. Hyperlink each author name directly back to their user profile page on the source site (e.g., http://stackoverflow.com/users/12345/username)
Instead, their author links lead to http://stackoverflow.com/questions/tagged/?tagnames=SOME-TAG-HERE&sort=active.
But they are following requirements 1-3. Perhaps a gentle nudge to point this out to them is all that is needed. (Go ahead and email them if you like; doubt I will.)