To be just a bit more constructive ...
In emacs there is an option to highlight parentheses pairs when your caret is on a parenthesis -- show-paren. Can a similar effect be achieved in TextMate?
If your caret is in parens, or inside a code block, you can press cmd- shift-B and it'll highlight the current block your in. The highlight will start from the beginning paren/bracket/etc and go up to the matching/closing one.
Not exactly what you're after, but it might give you a visual that might be as helpful.
Hope that helps, -steve