Working on Rails code for a bit has started me on the spiral into obsessively customising my dev environment (I say obsessive as at the last Rails meetup I went to there was
ProjectPlus and Getbundles are two great additions to TextMate regardless of what you're using it for. This blog post has details on both of them.
Other than that, if you know a scripting language (such as Ruby or Python—probably Ruby in your case), you can extend TextMate pretty easily to do specific tasks. This post in the TextMate manual has good information on getting started, such as how to get input piped from the text to STDIN.
An editor is only as good as what you make with it, so write some awesome apps! But if you're itching to refine your workflow a bit, these links should help.