Listen to your entire music collection on your iPhone and on the web. Have a virtually unlimted music library right on your iPhone. MeCanto is a revolutionary new service that lets you take your music collection with you, wherever you go, with virtually no storage limit.
You can now upload your WHOLE music collection online and stream it anywhere. 3G/WiFi, whichever… and for free. Seriously? That’s AMAZING! (Granted that still doesn’t solve the problem of what to do when you’re without a signal, but there isn’t much they can do about that).
Set up an account on www.mecanto.com and download the program to upload your music (PC only). Mac users you can upload manually, a pain, I know, but again, better than nothing!
Then open the app and enjoy.
NOTE: One major draw back is it doesn’t run in the background. With Backgrounder, however, you can override that flaw.
[Source - BigBoss] Cydia