Not the person you asked, but I am always consistently surprised at the success of survey monkey. I was a paying customer for two years though, mostly for reasons of replicibility. Many, many, social scientists use it, even though it doesn't really support useful things like randomisation to entirely different surveys.
The interface is nice, and they appear to have sewn up the marketing world, so well done to them. I still want to build a much better version, but I'm not sure if there's a market for it.
