Hackaday.io hacker [ajlitt] is looking for a way out of the WiFi bind. His solution? The Raspberry Pi series of chips has ... SDIO was that you could plug a GPS or something into your PDA ...

When working on DIY projects with Raspberry Pi ... reliant projects (e.g., GPS trackers or remote cameras). Bluetooth: Great for short-range, low-energy devices (e.g., wireless sensors or remotes).