English Russia has a gallery of snowmobiles made from scrap and repurposed materials. The one above is arguably the most awesome:
This bulky machine constructed by one enthusiast retiree from the Russian city of Kirov is powered by the old Yamaha motorcycle engine and is entirely made of scrap. Fiberglass seat was formerly a part of a small carousel, gear shift lever was a part of an unidentified old Coca-Cola souvenir. The front skies are covered with fluoroplastic, a material with extremely low friction factor. The main distinctive feature of this snowmobile is a big wheel instead of a regular for such kind of transport rubber heavy caterpillar made of metal and rubber. For this reason this monster is very light which allows it to drive on fresh crumbly snow.
They also note that heat from the engine will warm both the passenger and the fuel tank. There are a number of other interesting contraptions in the gallery, several of which incorporate propellors in the style of a swamp airboat (the last one at the link uses a rotary lawnmower blade mounted on an inflated innertube!)