I recently published a series of articles entitled How to Build a Long-Range Wi-Fi System that attracted quite a bit of interest. The series starts at http://rv.dickeastman.com/2012/01/how-to-build-a-long-range-wi-fi-system-part-1.html.
I used a 2.4 GHz High Power Wireless Outdoor CPE Model TH-WA5210G manufactured by TP-Link mounted on a flagpole that attaches to the ladder on my motor home. It connects to any wi-fi "hot spot" within a quarter mile or so and often to hot spots much further away.
I know from comments posted here that several people purchased an identical 2.4 GHz High Power Wireless Outdoor CPE Model TH-WA5210G or TL-WA5210G but had difficulty configuring it and asked me questions about it. To be honest, I did all this about a year ago and encountered little difficulty. I did not experiment with all the available options. It installed within a minute or two and today I couldn't remember enough of the details to answer many questions. I decided to take new screen shots of each significant step in the set-up process and post them here for others to see. Perhaps that will answer most of the questions.