Need Mobile Broadband Guidance

With the advent of streaming and on demand services (Netflix Instant, Rhapsody, etc.), I got an idea.

I want to know if such a device exists. And if it did, it would probably would fall into this category. Basically I want a device that has mobile broadband with digital outputs. I think it would be nice to have this amount of portability. I could take it to a friends house and listen to music, watch movies, etc, on a TV or stereo.

I know I can do this with a laptop, but a hand held device would obviously be more convenient.

Thanks.