I am relatively new to TextMate, having been converted from Emacs less than a year ago. Emacs (pictured below) has extensive support for coding in VHDL. I was quite surprised, then, when I learned that there is no VHDL bundle available for TextMate. It turns out that both VHDL and Verilog (the two most popular hardware description languages) are on the bundle request list.
When I think about this more, it makes sense. The Macintosh is not the platform of choice for hardware designers, who are probably using UNIX or Linux. The VHDL simulation software that we use in school only runs on Windows, but there are some command-line simulation tools such as GHDL that have been ported to run on Mac OS X.
I'm considering writing my own bundle, which would be a good excuse to buy that new TextMate book that I've been wanting. Syntax highlighting and commonly used snippets/declarations would be the main priority, followed in the future by GHDL integration. Of course, I would add the bundle to the Macromates SVN repository once it was in a useful state.