What is a good website to download music from to transfer to iTunes?

I have an iPhone and I want to put music on it for free. I want to be able to transfer it to iTunes and then sync it to my phone.

Amazon has over 50, 000 free songs
http://www.amazon.com/...zon.com/s/

All legally available for free download by their artists

Mp3skull.com
beepmp3.com