There are some innovative wood furnaces out there for whole house heating. There was a video of one on OD a while back, a search should find it...
hang on a tick..
These guys (I thought I'd saved the link...)
I've also seen some pretty neat solar solutions for hot water.
In either case you need to have a good idea of what kind of heat load your house has and, with wood at least, what amount of wood you can harvest repeatedly. My parents use wood to heat with and for 20 years or so have been able to do so with fallen timber.
Don't forget about the simple stuff like better insulation - the foaming kind - to seal cracks...