This is really weird. My Steam library is showing apps that it doesn't know what they are. Check out the pic.
Interesting... they may be legit stuff that I don't have installed: http://steamdb.info/depot/623/
Have you updated your client recently?
You may also need to refresh your library:
https://support.steampowered.com/kb_article.php?ref=3134-TIAL-4638