EcoGeek has a comparative review of residential wind turbines. None of these turbines would be a single-item install to replace all your electricity use, but they're affordable and if your electricty structure is anything like mine, taking the most expensive tier out of the bill would actually give you a financial payback pretty fast. It's on my list of back-of-the-envelope modelling articles to post an analysis of just what the energy and financial return might be for installing one of these.
If you're interested in making some estimates yourself, the Energy department has some useful data for windspeeds at 30m altitudes. (30m! no wonder many cities don't encourage them in urban settings.) Alternately, if you're lucky, you might find data for a Weather Underground station near you - however, I think most stations are rooftop vs on a 30m pole and so may be much slower.
