I was originally just checking out the dungeon generator, but I decided to click around and found a couple more generators, one of which I found particularly impressive.
Seriously, you should check out these map generators. The site itself isn't particularly impressive, but the content make up so much for the delivery.
There are some bonus files/pre-made maps on the site, but the "good stuff" are these three generators (click on the example map to go to the generator):
|Wilderness Map Generator|
Now these are the "big three" on the site, but if you browse around a bit you'll find other maps for your game as well.