Install 64 bit Ruby On Rails and MySQL on OS X
For a project that I am starting I wanted to use Rails and MySQL so I decided to install for source that I compile myself for both. It was amazingly easy and satisfying to have both compiled and installed on my machine for development. Hivelogic has some really simple easy to follow blog posts on how to do both. If you are wanting to compile and install either Rails or MySQL on your Mac from source code then I recommend you check them out.