I didn't see this in the list, but that doesn't mean it's not there.
It would be cool to have a back/forward functionality like in a browser. For example, I often use cmd-T to find a file to look up the signature of a class method or whatever. Then I want to go back to the last file I was viewing. If I have more than 8 files open, the tabs become useless. I could use cmd-W to close the file, but often times I have three files that I'm working on at one time and it would be nice to be able to just quickly switch between them in the order in which i've looked at them.
Browser-ifying the tab system is a pet request of mine that I hope to someday see realized. TextMate is an amazing editor - thank you again, Allan.
Ed