Remember Muxtape, that painfully simple yet really effective way of creating online mixtapes, err...muxtapes? I thought it would only appeal for us melancholy types who still can't get over the wonderful era of cassette tapes, but it caught on; there are many thousands of muxtapes available right now, and a couple of interesting applications grew from the concept.
One of these is Muxtape Stumbler, which allows you to find muxtapes according to artist or track. The former, unlike the latter, will yield results which don't necessary contain the artist you've searched for. It doesn't seem like much, but try it out: I swear it's the best way to discover new music right now.
Besides the search function, Muxtape Stumber also maintains a list of top artists, top tracks and top artist searches featured on the service. It's fun; the only problem, unfortunately, is that RIAA will probably eventually find out about it.
For alternative ways to search Muxtape see MuxFind, a straightforward but also effective search engine.