Last.fm, and wanted to see their release history) and I came upon (once of many times) StonerRock.com. Well if you haven't heard, this website is a great resource to anyone who loves stoner/doom/sludge metal. Something for any true fan to frequent.
Well because StonerRock.com doesn't have a search function (at least one that I can find), I googled some more, coming upon StonerRock.comp (officially at StonerRock.org). This .comp version of StonerRock is a website dedicated to the hosting of a compilation of unsigned stoner bands that frequent the site's forum. There are 9 volumes (so far), some are one disc some are two, but it is all stoner. I assume that at the time of the various compilations, the bands debuted were unsigned, but as I downloaded it all I recognized some names. Whether this means the band has gotten more exposed, or that my knowledge is far-reaching, I don't know. What I do know is that I now have over 100 tracks from a wide array of artists to enjoy.
Anyone who wants to hear some truly underground metal, check out StonerRock.comp for 9 volumes of stoney-goodness.