Before the WYSIWYG HTML editor in WordPress 2 came along, I relied heavily on a WordPress version of Textile to simplify my hypertext markup. I’ve been thinking of starting to use it again though, because of quirks with the built in editor, but Textile really grabbed my attention today because it was mangling a link with underscores in it (converting them to tags).
That got me to check and see if there was a new version of the textile plugin, and lo, there is, and it fixed the problem I was having. If you use Textile in WordPress, I suggest you upgrade too.