TextWrangler is my favorite editor. I made some plug-ins for syntax highlighting. Lately I have been writing assembly for Analog Devices SHARC processors and also a little bit of PIC16 stuff. Here are the TextWrangler plug-ins that I made for their instructions sets. To use them, copy them to ~/Library/Application Support/TextWrangler/Language Modules.
Updated both language modules fixing a bug which showed up in TextWrangler 3.0.