A short url for accessing this page is at http://nixgeek.com/fixmac/
Apple Discussions Support Forum - You can select the topic by OS, program, hardware or just type your problem into the search box.
CNET's MacFixIt Feed - Tech blog CNET keeps tabs on all their OS X-related updates with the MacFixIt blog. Head here to search for updates, cool features and troubleshooting.
Quora - Apple Products - I've linked directly to the Apple-Products section, but really just punch in whatever you are having a problem with and search. Answers are provided by other users of the service, I don't tend to use this all that much but others swear by it.
The MacRX Category on Cult of Mac - Cult of Mac keeps it simple: All Mac, all the time. Follow their troubleshooting-specific MacRX category to get updates on everything from good Mac maintenance and un-deleting files to how to fix start-up problems and get your Mac running fast.
Macworld Forums - Typical forum site with categories, search, etc.
macnn - Typical forum site with categories, search, etc.