David Porter founded 8 Tracks in 2006 and launched it just last year in 2008 with a global team. As a viable, legal alternative to Muxtape (and possibly Grooveshark), 8 Tracks permits a full 30 minutes worth of uploaded/streamed music (roughly 8 tracks of music, hence the name). Here's a great mix by tylr I stumbledupon:
Have a lot on your mind? Old lady got you down? This mix is for you. Turn off your cell, dim the lights...and turn the A/C down to 60. It'll all make sense.