You have about 36 hours, until midnight tomorrow (Saturday April 30), to get a set of 3 Lexar 16GB Platinum II 200x compact flash memory cards for only $99 at Adorama. If that price isn't tempting enough they're offering free shipping and are throwing in a memory card wallet to boot.Not only are these cards fast, but they also hold a bunch too, one card will hold up to 3,200 16MP images (or 2,300 21MP images). Video your thing? One card will hold up to 6 hours of video.
A perspective on just how good a deal this price is their competitors are selling the exact same memory cards at $87 for a set of (just) two. Plus the cost of shipping and no wallet.
If you don't need quite so much card (or want to spend quite so much money) you can get the exact same card in the 4 GB size for just $18 each. Free shipping on these as well.