Note: These items are for the Blog Action Day regarding the environment and are not prescribed for those with weak hearts.
By being homeless, you can save on rent, electricity, water, gas, trash bills, home repairs, furniture, etc. You will be closer to the natural world and it will help you appreciate the ecosystem that we live in. Need a bathroom? There's always the national park toilets that use no water you can use, plenty of restaurants, or the good old trusty log and hole in the ground. Need a shower? Many truck stops have showers, the local gym has one and there's always a stream or lake one can use. Besides helping the environment by consuming less, you'll be saving lots of money.
Have No Children:
How much of an environmental footprint does each person leave? One sure way to reduce the number of people leaving an environmental footprint is to not have children. This will also free your time up to go out and plant trees, clean streams, and protest the latest polluters. Being homeless is not the best place to raise children anyways. If you really want to have a child, there's always adoption or foster care.
Working at a job producing widgets? Does your company recycle as many widgets as they produce? Most places don't and they don't worry about them filling the environment, that's "somebody else's job". Leave that place and change careers into one of many jobs that do: Waste Water Specialist, Sanitary Engineer, Farmer, eBay Seller/Buyer. You'll be bringing the world back to it's natural state instead of filled with widgets.
Note 2: I don't follow any of these tips, but I do many of the common environmental tips (recycle as much as possible, compost pile, CF bulbs, reduce heat, turn lights off, consume less, drive high MPG vehicle, drive little, organic garden, reuse stuff, shared housing, cloth diapers, second-hand shopping). Enjoy these radical ideas and have a great day!