The folks over at SanDisk sent me a heads up on a special deal: if you want one of those combo SD cards with USB capabilities, SanDisk has them discounted for just a few days. The 1 GB, Ultra II SD plus USB is only $59.99 through May 24th. I just checked BestBuy and they’re selling the same card for $89.99! If 512 MB is more your "flavor", you can grab that one direct for a special $34.99 price.
I didn’t pick one of these up simply because my tablet has a built-in SD slot; if not, I would have grabbed one of these cards a long time ago. The design is ingenious!