The Green Bay Professional Packet Radio group (from Green Bay, Wisconsin) is a rare group, coming at wireless networking from a solid background in radio technology. While they are not particularly focused on 802.11b, they have a huge wealth of information about radio design. Exotic technologies such as laser beam point-to-point links, fractal antenna designs, and home-brew spectrum analyzers are just some of the fun things you’ll find at GBPPR. Their main page is online at http://www.qsl.net/n9zia/index.html.
They also host a bunch of insanely useful interactive calculation tools. If you need to figure out fresnel zone clearance, antenna tilt and bearing, or the amount of gain required to bridge a given distance, you must check out their free interactive radio design software. You can find them online at: http://www.qsl.net/n9zia/wireless/page09.html. In particular, I have found their Wireless Network Link Analysis tool invaluable for estimating path loss and link budget (see Chapter 7 for some examples of how to calculate this for yourself, then use their great online tool to play “what if”).