Based on a recommendation found in Practical Sailor I purchased and installed the Bitstorm WiFi extender.
There are two parts to the setup. The Bad Boy Xtreme (great product names!) is at the top of the mast and the Unleashed repeater is down below. This system has been installed on the boat for over a year and it really works well. Everything is configurable from a we browser and the I can pull in WiFi signals from a good distance. Many times I have found that my Shindig WiFi connectivity is better than I get from AT&T DSL at home.
Before I made the purchase I called Bitstorm to clarify a few things and get some advice on rail mounting or masthead mounting. They were very knowledgeable and friendly to work with. I have no regrets on this Shindig upgrade.
On a recent trip to Drakes Bay we had no cellular service but I was able to poach a WiFi signal from somewhere on the hill. Nice!