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.
Commercial Use
Modify
Distribute
Place Warranty
Use Patent Claims
Sub-License
Hold Liable
Distribute Original
Disclose Source
Include Copyright
State Changes
Include License
Include Install Instructions
These details are provided for information only. No information here is legal advice and should not be used as such.