I need some help...

I currently subscribe to Napster and have an account at Pandora.

I'm not burning or ripping anything.

So I use Napster to put songs on my MP3.  I'm not using it for streaming because it's not "smart" like Pandora.

I'm using Pandora for streaming, but you can't transfer anything to a MP3.

I've looked @ Slacker, which is nice, but I don't want to go jogging with my two-pound blackberry.

So...

I need help finding a site which acts like Pandora but can support an MP3 portable like Napster.

Can anyone help?