Earth Day activity: Make a worm compost bin. Tips for how to make one, What and what not to feed your worms, what to do with the resulting compost etc also there's a book I want to check into Worms Eat My Garbage, by Mary Appelhof;
Generally, people think of composting as requiring a designated compost pile. Trench compost piles become their own productive garden plots in just a few months. This reduces the need to disrupt healthy soil micro-ecosystems by digging up and transporting compost from the compost pile to the garden.