Install Rails/lighttpd with DarwinPorts for Tiger

install darwinports package

Add 'export PATH=/opt/local/bin:$PATH' to ~/.bashrc

sudo port -d selfupdate

sudo port install ruby

sudo port install rb-rubygems

sudo gem install rails --include-dependencies

sudo port install readline

sudo port install lighttpd

vi /opt/local/etc/lighttpd.conf [edit lighttpd.conf to your liking]

set up launchd item for lighttpd
        -- restart lighttpd: sudo launchctl stop net.lighttpd
                             sudo launchctl start net.lighttpd

sudo port install fcgi

sudo port install rb-fcgi
         
install official OS X MySQL package (not darwinports)

sudo gem install mysql -- --with-mysql-dir=/usr/local/mysql

Links:
darwinports package
launchd item
OS X MySQL package

Restart lighttpd script

I use this script to avoid having to do the killall dance on my local dev box constantly when tweaking my lighttpd.conf

#!/bin/sh
sudo killall -9 lighttpd
sudo killall -9 ruby
sudo /opt/local/sbin/lighttpd -f /opt/local/etc/lighttpd.conf

Make the script executable (chmod u+x), put it in your path, invoke by simply typing the name of the script. This also kills off any ruby processes, which lighttpd will restart when it reboots.

The path to lighttpd and the lighttpd.conf files are based on the installation from DarwinPorts - adjust as needed.