I've had a couple (2 or 3) of occasions with TextMate crashing and all those times, it happens doing exactly the same. However, this isn't reproducible in the sense that I can make it happen anytime I want to. That said, what happens is the following:
1. Cmd-F to bring up the Find dialog box.
2. Fill in the text to be searched.
3. Press <tab>.
4. Boom.
Each time, I send a crash log to Macromates and Apple, but I haven't seen this problem on the list. I know of one other person who also had this happen. Are we the only ones? :(