I played with a coworkers Rio S50 earlier today, and I am impressed. The little device had so many things hidden away in the software, and getting around was easy. The screen also displayed an impressive amount of info.

Overall, it seems like a good solid state player, and it uses standard memory formats (MMC) for expansion.

One thing I couldn't figure out though, can it use the SD cards? I can't find any 256mb MMC cards, but 256mb SD cards exist.