If you have, or can develop, machinist or craft skills, there are opportunities to start a business along these lines as well. These kinds of businesses are also well suited to low-overhead operation.
Here is a link to a very popular thread on the Popular Machinist forum on starting one's own craft or low-tech manufactured product business.
There are many available niches where a product or a service can solve a problem, even in a down economy. String enough of these opportunities together, and you can cover more of your monthly overhead--sure beats working at the Home Depot.