I would also gladly pay for a new version with a working undo feature and the ability to split the view. Off the top of my head, I can't think of anything else that I really feel I'm lacking, but I feel the lack of those two things on a daily basis.
And, without meaning to start any kind of 'editor war', I do note that the MacVim team have now managed to create a version of vim that doesn't look so out of place on a mac, and I'm sure the same is true of the various emacs ports. And all of the rest of the competition.
Textmate's competition is not standing still. Which is not to say that there should be a version for the sake of it - far from it. But...but...it is hard not to be impatient for those improvements which would make a big difference to daily use.