This is a cool little Web site.  Being that I'm well over 15 years removed from 7th-grade grammar instruction, I often find myself questioning sentence construction, word choice, etc.  (How many errors were in that last sentence?  Sheesh.  I couldn't even tell you anymore.)  Grammer Cop has a helpful reference section of questions submitted by users, and if you don't see what you need, you can just ask!

http://grammercop.com/joomla/index.php