WiMax is a micro-wave style point-to-multipoint "ethernet" connection. For people too far from DSL central offices and not on "Internet capable" cable systems, it's a really good choice. Think of it as DSL without the wires. Older versions of WiMax were actually 802.11 wireless with high-gain directional antennas. By putting 20db on the primary lobe, we could get some good distance without violating the "100mW total radiated power" rule. Wimax runs in the 5.2Ghz band, where regular home-style 802.11 typically runs in the 2.4g range.
For personal "no monthly" point-to-point connections, I still think this is one of the best ways to go (assuming LOS and rooftop access).
Speeds and distances vary - the longest haul I ever installed was about 6 miles. As with all LOS systems, you really do need to be able to see the tower at the 'central' node where the head-end/repeater is. A company called 'Tranzeo' was where we got all of our equipment.