I have written a macro for JEdit that allows you to jump around from one related file to another in your Rails project. The behavior mimics some of the capability of the TextMate Rails bundle. This screencast shows the macro in action:
***Update - 07/04/08***
At long last I have finally decided to post this macro to a highly-available public repository. For the longest time, I have been hosting the zip file for this macro on my home network and many times the server was unavailable when someone needed it. No longer! You can download the macro from this github repo.
You'll want to copy the 'Rails' directory into your <home_dir>/.jedit/macros directory. You will need to have the Ruby and SideKick JEdit plugins as well as the "ruby" executable for your platform visible in the "path". This macro has been tested on Windows and Linux (OS X users will have to settle for TextMate ;-) ).