Some are using it with good luck. Im not.
There is Iuma.com which I think is the best overall. You need to make up a Bio there. Theres also http://www.broadjam.com/
I havent had any problems there.
Also worth noting - If you put your song(s) on mp3.com, many people in the clinic will skip over it, due to the fact that you have to register to listen to mp3s on mp3.com
Like Dobro said, Save your recording (if your using a computer) as a mp3, or if your using a tape recorder or DAW, just burn your recording to cd and then upload it on your computer and make it an mp3. Then Go to www.nowhereradio.com and get you 15megs free space to post your songs. Then go to the Mp3 mixing clinic (that's on this site) and write a thread and type your link. (like if your name is "Adam" and your at nowhereradio.com, your link would be: www.nowhereradio.com/adam/singles )