They were selling these (www.wdc.com) at Costco a while ago. My dad has one. They're pretty decent for playback performance and quality, and one of the few DLNA-type devices I've seen that support MKV files, as well as can do 1080p, and subtitles to boot.

I think it requires an ethernet connection, but they make pretty long cables.

Also, last I looked, there was sort of a "hacker" community around rooting the boxes and turning them into embedded Linux boxes. Might be a way to get a web browser on it, if that's important.