Qi-Hardware atben and atusb
Qi-Hardware has a bit of an obsession with free, open source, and underpowered. The latest project from this descendent of OpenMoko is a set of license free wireless boards called atben (for the company's Ben NanoNote) and atusb for other laptops. The adapters rely on the IEEE 802.15.4 standard which powers 6LoWPAN and ZigBee. Don't get confused though, this is not a replacement for WiFi -- it's more like long range Bluetooth (and it's not compatible with either). Ben WPAN, as it's being called, has a range of about ten meters in "standard" mode while pushing 250Kbps. Turning on the "non-standard" mode boosts throughput to (a still patience-testing) 2Mbps, but cuts the range in half. You can pick up pre-built adapters starting at €29.50 (about $42) for the atben, €41.30 ($59) for the atusb, or €59.00 ($84) for both at Tuxbrain. Don't expect to just jam one into your Mac however -- for now at least, Ben WPAN is a Linux only affair. (How often do you hear that?)