I've written about FortiusOne's GeoCommons application almost exactly one year ago. It was an advanced app that let you create advanced, custom maps using various geo datasets.
A year has passed, and GeoCommons is no longer available in its initial format. It has become a suite which will consist of three intertwined applications: Finder, Maker, and Atlas. I recon that the three applications put together will be a more powerful version of GeoCommons, however, only the first one, Finder, is available at the moment
It's a search engine that lets you search for geo datasets or browse through categories or tags to find them. Once you've registered with the site - which is currently in invite-only beta - you can save datasets to your own profile and share them with others. Finally, if you want to contribute, you can upload your own geo datasets to Finder as well.
The datasets included in Finder's database still seem to be sparse. For example, the "Technology" category will yield very few results. As far as the actual search goes, I've noticed that "OR" operator is turned on by default instead of "AND", so expect some very wide results. For precise multi word queries, use quotation marks. Still, I can't think of any other better or at least equally elegant way to find geo datasets on the net, so I'm sure there are a lot of people who will find Finder valuable.
When I wrote about GeoCommons I've noted that the application is not really aimed at the most casual users, but rather at professionals who are used to working with geo data. This also holds true of Finder; while it's really simple to use, most users won't have any idea what to do with the geo datasets - especially those in ESRI format, which is used only by professionals - except perhaps load them into Google Earth (.kmz is also supported) and look at them.