zd1201 USB Wireless Adapter
The Airport Extreme in the iBook is currently a lost cause for linux (curse Broadcom), but the workaround is fairly cheap and not too inconvenient. I bought a GigaFast WF741-UIC 802.11b USB wireless adapter, which has the ZyDAS zd1201 chipset, and it works great in linux. I haven't got kismet to run yet, although it does do monitor mode and I've heard of people getting kismet to work with the old wlanng-based driver, so it's probably just a matter of time.
The driver (but not the firmware) is included in 2.6.12-rc5, but not 2.6.11.10. So I recommend picking up a 2.6.12 or higher kernel, but aside from a poorly-packed tarball building the module separately isn't hard either. I had trouble getting Ubuntu to load the firmware, and the solution is apparently to get more recent hotplug scripts. It has worked perfectly in Debian from day one.
waproamd doesn't want to work, nor does wpa_supplicant, so I'm writing my own autoconnect scripts. That's ok though, because I've never really been impressed with waproamd, and wpa_supplicant is much too complicated for simple wep authentication. The saddest thing, right now, is that I can't just put the computer to sleep and have wireless when it wakes up. I have to take the card out before sleep and put it in after, and since I don't yet have it automatically configuring I also have to configure it on resume too. I've seen a patch for this, but it didn't work for me.