In updating myself I found some really useful Rals plugins for my next project.

Hoptoad Notifier
A Rails app is a very dynamic thing. Finding out when your users have errors, and what the pattern of errors is a must have. The traditional approach is to view the log files from time to time, or use a notifier that sends the errors to your email. Then go thru it as they come in. First, it not uncommon for a error to repeat. So you get log of junk in your email. A better approach is to use the hoptoad service/plugin. This way, you get nice reporting and analysis, and for a single project, its free. It consists of a hosted site web gui, and a rails plugin, and a optional local mac gui to show your croak's, ie the errors in your apps.

http://www.hoptoadapp.com/welcome
http://blog.railsrumble.com/2008/10/6/hoptoad
http://github.com/thoughtbot/hoptoad_notifier/tree/master
http://github.com/bricooke/croak-app/tree/master

Simple Ruby Rest Client
REST is a lovely way of doing Remote Procedure Calls. It the rails way of creating web services. Sometime its handy to have a simple REST-client.
There is a simple to Rest client done by Adam Wiggins

http://github.com/adamwiggins/rest-client/tree/master
http://rest-client.heroku.com/rdoc/

Now you can call a REST api even from IRC or rails console