There is still plenty of tweaking to do, but for those who like Access (or for those who don't like it much, but use it anyway), I've created a GTD database app (147k zip file).
Right now to alter context, priorities, etc., you need to know a little about Access and get into the tables. I'll release updates as I change things.
Keep in mind that this was a quick-and-dirty. I'd like it to be a lot more complete in future. If you have ideas, leave 'em in the comments (note: comments are moderated, so be patient).
Sweet! I've run across a couple of MySQL implementations which are too deep-geek for me, but I can handle Access. :-)
Can't wait to try this out. I'll send notes your way...