By now, most of us who claim affiliation with the OSR know about Dave's Mapper, the nifty map generator that uses geomorphs created by a variety of bloggers in the OSR blogosphere. It's a cool tool that's only getting better as more folks submit their geomorphs and Dave plugs away at expanding the options.
And maybe you've also seen the Dire Press d20 Random Dungeon Generator. Or the Dizzy Dragon Dungeon Generator. Or the Myth-Weaver Dungeon Generator. Or all the goodness at Djerv's Graveyard, where Djerv has not only dungeon generators, but a nice set of other adventure generating tools.
But did you know that Wizards of the Coast tried to jump in the fray, too? Here's the old dungeon generator at their site. It's functional, but the fan-created stuff is much more impressive.
And if you dig around on the WotC site, you can also find a dice roller, along with the necessary files to run it offline locally from your hard drive. Some random guy on the internet took these files and cobbled them together to make a Dashboard Widget for the Mac. This works well on Mac OS X 10.4.11 (Tiger) for those of us stuck on older machines.
And also in the dice rolling arena, I stumbled across this application for us Mac users: bones. It's a pretty nifty piece of software. I heartily recommend you download it and play around with it.
I know that the technology focus is shifting to iOS and all the groovy apps for your iPad, iPhone, and iPod Touches, but some of can't afford these news toys, which is why I always keep my eye open for these sorts of software tools.