How can I stream my music library to my iphone?

I know about the Last.FM app for the phone, but that's not what I'm looking for. Basically, what I want is functionality similar to the ipod application on the phone, but I want it to be able to access my ENTIRE library from home, and allow me to select which songs play- not like the random selection on last.fm. Is there anything out there that can do that? Thanks