I messed with this one a bit while in Beta, now you can get your own invite and its way cool! From the developers… Finder! (a browser-based application for finding, organizing and sharing GeoData in common formats) has officially graduated from ‘private beta’ and is now open to everyone for finding, organizing and sharing geodata. To get started, simply sign up to create a free account. See also http://www.geocommons.com/
See also http://finder.geocommons.com/
Use the search UI to enter your search parameters i.e. “Colorado Parks”
Then access metadata, preview your data in Google Maps or Google Earth, or download as KML, SHP, or CSV