When I started this, it was tricky to get Rails up and running. With the advent of Mongrel and better Ruby packaging in Linux, it's easier and AxleGrease is less important. So I won't be updating it much. If you want to take over, please contact me.
FirePHRuby let's you use the "FirePHP" Firebug/Firefox extension (http://www.firephp.org/), which is very useful for AJAX development, with Ruby. It can be used in CGI, with Rails or with plain WEBrick or Mongrel