I use the latest version of textmate for all my Rails development needs and I feel that I\'m under-using the possibilities or this software. I only installed the Ruby on Rails b
I've been using TextMate for a while now, and one of the best things about the application is the ability to extend it using bundles. As Yaraher said, there are lots of resources out there, and you should go and take a look.
My only other piece of advice is this: when you find yourself doing something with TextMate over and over, and it is a pain, or you think that it could really do with this or that feature, think about how you could do that with your favourite scripting language. If you can write a script for your feature, you can add it as a command that TextMate can use - have a look at the bundle editor (Ctrl+Opt+Cmd+B) and the existing commands, it is pretty straightforward.