I have recently discovered www.8tracks.com/boyred where i have started to post some mixes. I have reposted those listed on the Mixed Up Boy Page as the original postings on www.soundcloud.com/boyred are long and using up my timed capacity. 8Tracks is a great way to hear new music. You can only post individual tracks at this point. Must be over 8 in number and not more than two from any given album. Check it out.
Update: December 2019 8Tracks has finally thrown in the towel after struggling financially for some time - it'll be missed.