Recently I had to vent my bathroom fan properly (previous home owner vented it to the attic). Obviously it was much warmer up there and I was wondering if I could install a fan in my house to pull warm attic air into a common living area. I know attic air has a lot of moisture be we also use a wood stove in the winter so that could help to balance the moisture. Good idea? Bad idea?

I think it would be a bad idea due to the moisture from the attic. You only think the wood stove will help balance out the moisture problem but I don't think it would. It would only make your home much more humid and ruin any wood furniture you have. If your home is okay now in the winter without extra "supplemental heat" as you put it, leave things alone. Would try some extra insulation in the attic first.

I think it is a great idea!
Anyway, why would there be more humidity in the attic then in the house... the attic is probably drier than the house. I have seen studies where temp and humidity probes were placed in the attic and the amount of useful heat all year long is quite dramatic. I have heard of a company doing this for motels and cottages and it seems to be working for them... check out heat-booster.com

Its not likely you are going to have any heat in the winter to be helping you in the living area