Okay.. so my MacBook crashed... I hadn't backed up and had to replace the hard drive completely... nothing was retrievable

I still have my itunes library on my iphone and was wondering if there was a way to do a reverse sync or something? When looking to sync music, itunes is saying that it will wipe my iphone and replace with the current itunes library (which has nothing!)... any ideas on getting the iphone library transferred to the computer?
HELP!
