You know you’re a geek when you enjoy spending the better part of a day downloading, installing, and configuring software.
And now that I’m on the other side, I have Rails on FastCGI running for both Apache and LightTPD.
On the Apache side of the house, you want to read Dan Benjamin’s Do It Yourself Guide to Installing Ruby, Rails and FastCGI [on Mac OS/X]. When you get to Virtual Hosting, then mezzoblue’s Virtual Hosts for Dummies is what you really want to read.
For LightTPD, Dan’s Building Ruby, Rails, LightTPD, and MySQL on Tiger is the definitive guide. With James Duncan Davidson’s Virtual Hosting Rails Applications with LightTPD for Virtual Hosting.