I was googling for random dungeon generators and found Jamis Buck's Random Dungeon Generator files on Archive.org. There's source code there and a Windows executable - the screen shot above (click to enlarge) is running inside of Wine on OS X. Jamis released this as free software years ago. The maps it generates aren't super complex but could be useful in a jam or further GIMPed or photoshopped. The actual room contents (D&D 3.5 stats) it generates are a nice touch.
(Update: Looks his perl script is still hosted on at least one other site too.)