Along the same lines, micro-turbines are also pretty neat. They are generally similar to turbines used for co-gen in large facilities. The smallest I've been able to find is 30kW, which isn't really suitable for home use, imo. However, gas turbines are a more "established" technology than Stirling engines.
http://www.capstoneturbine.com/prodsol/products/
Edited to add: Smaller systems are in development. This company in the Netherlands has a 3kW microturbine that they're developing. It only does ~50,000 btu/hr for hot water, which wouldn't be enough to heat a house here. You'd either need 2 or supplementary heat for the coldest days.
http://www.mtt-eu.com/applications/micro-chp