Among this weekend's projects was a compost bin. It's loosely based on the plan here--three bins about three foot square each, with lovely slide out slats on the front for easy access to the good stuff later.
It actually only took about two hours, and that was even counting time for making the measurements up on the fly because we were trying to use up scraps from the fence. (We opted not to bury the posts though, which probably would have added another hour, at least.) Yay for homemade compost!