Sansa has had historically poor results in taking on the Shuffle, but the slotRadio looks a smidge more marketable. It's a few dozen follicle widths thicker, and joylessly gray, but it packs a tiny LCD screen for navigation into its tiny, clip-on frame... an immediate plus. Better yet, its more fully functional, containing an FM tuner and an expandable microSD slot capable of handling cards up to 16GB.
But for $99, you get more than the hardware: you get a library of 1,000 tracks preloaded, cherry picked by Billboard according to mystery criteria that probably reduces to "catchy, but low royalty." As an extra perk for a clip-on MP3 player, that's not bad, but I'm not really sure of Sansa's attempts to sell pre-loaded MP3 players as a long-term business strategy. It seems to confuse the PMP for the medium when its really just the hardware: surely no one got rich in the 80s selling Walkmans pre-loaded with the manufacturer's own personal mix tape.
Sansa slotRadio to take on iPod Shuffle? [PMP Today]