Quick deal alert:
Until Sunday, September 18th, make $500 in SkyMall purchases through this link, and you'll receive 25,000 Delta miles. That's a pretty great deal: Even if you value Delta miles at only a penny each, its like getting $250 back from a $500 spend.
One of the best items I've found on SkyMall for $500 is the Samsung Galaxy Tab 10.1. If you don't yet have a tablet of your own (or you want to gift one to someone), this might be the time to do it! There are two versions of the tablet: one for $499 and one for $599. If you go for the $499 one, make sure to also purchase something else to get over the $500 threshold. Taxes and shipping don't count. You can find the tablet by searching for Galaxy Tab in the SkyMall search box.
If you don't need a tablet, you might also checkout Samsung TVs and monitors. I own both a Samsung monitor and TV myself and they're both great!