I have a monocog set up as a fixed gear. It's geared low with flat pedals and big fat SB8 tires. I use it to terrorize the neighborhood. I wouldn't want to commute on it, except maybe in extreme weather.
I use a 29er with 2.10 knobby tires, the gearing is 36-15. I use it if I have to ride to the store or on a 10 mile or less round trip. It's actually a lot of fun, and we get snow here too so I always break it out for bad weather.