ipaq 2215 -- Amazon says it qualifies for the $50 giftcard.
In my case adding a wifi card would let me roam around the house playing music from my FLAC jukebox, sweet!
Less gadget-y, but a little over $500 would get you a decent receiver from etronics plus a pair of Polk RT28 speakers on sale at Crutchfield. Music sounds much better to me with decent bookshelf speakers than with tiny sats and a sub.