mSpot

Very excited about this service. For $4 a month, I get 40Gb on online storage for my music files (currently 28Gb worth) which acts for me as a backup PLUS there is an iPhone app that will let you display the library and stream the music to your phone!

This saves 13 Gb of space on my iPhone (more room for movies/tv) and individual songs download very fast over 3G. LOVING IT!