Guys,
There quite a few in the market now a days. These are called "Portable Media Players" HDD based. I just bought one couple of weeks ago from Dubai. My brand is "Merlin" with 60 GB USB HDD and it's 6 in 1. Picture will be of some help to get some specifications.
Basic features are:
1) MP4 Video Player
2) MP3/WMA Player
3) Photo Album, & Backup
4) USB 2.0 External Hard Disk
5) e-Book Reader
6) Voice Recorder
It also came with a FM Transmitter which connect to Car cigarette lighter socket and then you can choose any FM frequency to transmit and tune your car FM Radio to listen to your music stored on your hard disk.
But the best thing about this Mobile Theatre is that you can record from any AV source or from your PC/laptop and it has also AV out option to project on TV, LCD, Multimedia projector etc.
Any body wants to enjoy his DVD movies OR MP3 Songs to listen or watch in your car then you need to first connect the AV output to your Car LCD or Stereo system and enjoy the Mobile Theatre.