BEFW11S4
Jim gave me his Linksys BEFW11S4 (802.11b base station) when he left for Germany. Turns out I already had one, but mine is a bulky older version, whereas Jim’s is the v4 which is both slimmer and more powerful. Unfortunately, the v4 causes devices with Airport cards (not Extreme) to quickly enter a hard freeze.
A little Googling revealed that the best thing to do, in addition to updating to the latest firmware, is to do a hard reset: Hold the reset button down for a long time (30–60 seconds, depending on whom you ask), remove the power, restore the power, then release the reset button. The result: No more freezes.