For home builts:
This is a practical size, and a proven design: http://www.scoraigwind.com/
This is bigger, and not too many have been built: http://prairieturbines.com/index.htm
Otherpower, mentioned above, is a good site. Home Power magazine has frequent articles on home-sized wind genrators. http://www.homepower.com/
I would say that anything under 1kw or under 8 to 10 foot blade diameter is a "toy" and the costs of a proper tower become a larger proportion of the cost of the system. Beware of anyone telling you that you can mount a wind machine on a roof.
I have been using a 1940s vintage Jacobs machine since 1978 or so. It has 14 foot diameter blades, and the generator itself weighs about 400 pounds. It is on a 60 foot tower, which is about 40 feet shorter than I would like. Also, our current location isn't as windy as the place we used to live, so we get 100 to 150 kw-hrs a month from the generator.
The tower and generator are another 250 feet up the hill from where the people in the picture are standing.
I wish I could find it now, but one of the coolest looking micro-wind ideas I can remember seeing was somewhere in Asia (I think) It was basically a greenhouse with parts of the wall removed and replaced with thousands of intermeshing plastic turbines (about 2-3" diameter) that had a gear-ring around the outer edge. The gears all meshed up with all the others around them, and in turn turned several generators around the periphery. The idea was that the greenhouse could make a "wind" by creating a temperature differential pretty much any time of year, plus it could be used to grow crops.
Savonius turbines seem to have this aura of badness around them... Not that they don't extract power, but every time I read about them - someone else knocks it down for efficiency... I think they're pretty cool in that you can take a stick, pringles can and small motor from a dumpster and produce power. Sure, it's a small amount, but at a cost of free
I saw those micro turbines on the Makezine blog a few months ago Totally cool, until someone suggested setting them up next to roads in otherwise windless areas
Time is the best teacher. Unfortunately it kills all its students.
The Savonius has my attention primarily due to the vast degree of scalability. One could be installed by itself, and sucessive ones could be installed right next to the last, increasing the effective efficiency of each by roughly 25% through vortex effect on it's neighbor. Likewise, they could be mounted virtually anywhere and sized to suit.
I see a glaringly obvious place for these things in hydro-power. Mounted along the dam line which could act as a natural funnel, there is allot of untapped potential along any lake that regularly gets windy. Similarly, right at the peak of the roofline would be the ideal place to mount them on a home.