Every song you listen to or add as a favorite on imeem Mobile is reflected in your media tracker on the Website proper, and vice versa. So as you listen to songs while at your desktop, every artist you mark as a favorite will be available to you when you walk out the door with your Android phone.
This is basically like Pandora, but runs on the T-Mobile G1, which launches Wednesday. Imeem is a music streaming website, allowing you to choose your favorite artists or songs, and it will create a playlist for you with similar songs. Imeem allows you to favorite, block, pause, and skip, and contains music from all 4 major record labels, so most artists are in the library. It will run on wi-fi or the 3G network, making it truly mobile. Reviews are positive thus far, so this may be worth investigating!