If you write RubyOnRails code on your mac, you definitely have to use Textmate for it. Yeah, I know. Pay for a simple text editor? Just try the 30 day trial version and you will see it's worth it.
The theme I am using at the moment is the Railscast Theme by Ryan Bates. You can find it in the about section of his Railscasts. Dark background and nice font colors. When you look at the code the whole day, it should look good . Don't forget to download the Bitstream Vera Font.
Ack is one of the greatest scripts I know. Grep for coders. Fast, easy to use and very good defaults when searching for code snipplets.
If you want to use it within Textmate, you should try AckMate.
Need better project support including features like git? Use ProjectPlus.
Speaking about git. What about github? Yes, there's a bundle for that . DrNic's github bundle.
Ruby On Rails Bundle
Dr Nic's most important Textmate bundle is the Ruby on Rails Bundle. With it you can easily navigate between controllers, models and other files. Besides that it adds tons of shortcuts. Whatever you will need for RoR development, you will find it in there.
If you want to keep track of all chrome extensions I use, you can subscribe to my links on Pinboard tagged as Textmate.