Probably the closest equivalent of Rio now is iRiver, in that they cram in as many neat features as they can think of, sometimes at the expense of usability. I don't think they ever made a player as good as the Karma, but netiher did they make a player that unreliable.
If you want a player that simply does what it claims to do (very, very well) then there is nothing to beat an iPod. The Video edition is gorgeous, and available in black
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Although I've bought several iPods as presents recently, I can't bring myself to use one while my Karma is still ticking (umm, or in fact, not ticking, 'cos that would be bad).
Rob