This is a simple, cool service that will no doubt become ubiquitous in no time (am I late on the trend? is it already passe?): Muxtape.
It's a super-simple mixtape site where you can load up your own tunes for easy share in almost lickity-split time and check out a world of others.
C'mon down and give mine a try: catfishvegas.muxtape.com
(Give props in the comments - using the metric system if at all possible - and shout out your own muxtapes!)