Forced air - it gets very dry around here in the winter (especially during the recent almost-drought). Our house is tighter than when we got it (new windows) and the furnace is much more efficient and uses outside air for combustion, but it still gets dry enough inside the house for static to build up (and our sinuses and throats to dry out). Just another one of the hazards of modern life...

Thanks.

Cheers,
Scott.