Geekzone's got a review of GlobalSat's SD-501 SDIO GPS receiver, which looks to be pushing the limits of how much stuff you can stick onto an SD card. That big thing on top is actually an optional booster antenna, which Geekzone says'll give you "marginally better reception." While it looks like it'll get the job done, this probably isn't the best solution if you're going on a long distance trek or grueling geocaching adventure. And at about $135 it's a bit pricey just for casual use. But if you've got a jonesing for GPS, and something like a Bluetooth GPS receiver isn't an option, it might be worth a look.