The Mac OS X Hints site gives handy tips and tricks for all things Apple.
Quoted from the MacOSXHints website
I should first say that OS X public beta was my first real exposure to UNIX, and that's probably one of the bigger reasons for this site -- a good friend of mine is a UNIX wizard, and I'm sure he was getting tired of my calls! While trying to learn the system, I was getting somewhat frustrated at having to jump all over the web to find answers to OS X questions. There are some excellent sites out there (make sure you check out the links pages here), but none that seemed to focus specifically on providing how-to's in a quick, easy-to-use format.
So in November of 2000, I launched macosxhints.com ... and in the last five-plus, it has grown into a collection of thousands of hints regarding OS X and related applications, with multiple thousands of comments from experienced users providing even more information. It's truly a one-stop-shop for OS X hints and how-to's, and I'm amazed at just how intelligent and friendly the macosxhints community is!