Use a credit union instead of a bank. A credit union is owned and run by its members for their own benefit. Find a credit union near you.
Support cooperative businesses. Co-ops are non-profit businesses run by and for members. Sometimes you can even find cooperative utilities. Check out the .Coop Directory.
Try crowdfunding. As a creator, it lets you make money from your creativity. As a patron, it lets you buy goods and services directly from the people doing the work, so you can get great stuff and support private business. Options include literature, artwork, crafts, music, webcomics, and much more. See my article "Crowdfunding: A Communal Business Model." Check out crowdfunding to promote a project of your own, review projects you patronize, find new projects to explore, and/or discuss this alternative business model.
Buy local. When you spend money at an independent local store, more of that money stays in your community and may make its way back to you. Spending money at chain stores will just send it far away. Most towns have a Chamber of Commerce listing local businesses. You can also search for small businesses online.
Reduce or eliminate your dependence on chain grocery stores. Shop at a food co-op, farmer's market, or community-supported agriculture program. Grow your own food.
Avoid chain restaurants. Learn to cook. It is cheaper and often healthier to eat at home. If you eat out, favor independent restaurants.
Take charge of your own entertainment. Hold a games night for friends and family. Learn to play a musical instrument and/or sing. Write or tell stories. Take up a craft or other hobby, preferably one that requires no materials or stuff that can be found locally cheap or free. You don't have to depend on big publishers, music producers, Hollywood, etc. -- and if you're like me, you probably find that a lot of mainstream entertainment sucks anyhow.
Practice barter. You may run out of cash, but you always have your skills and often have extra stuff you don't need. Somebody out there is probably wishing they could afford to pay for what you do ... and some of those folks probably have stuff that you wish you could afford. Skip the cash and swap goods or services directly. Learn about barter networks for wider reach and flexibility.
Watch for local currency. Because it can only be spent within a specific community, it keeps value in the local economy instead of letting distant people suck out all the money. The worse shape a society's official tender is in, and the scarcer it is, the more useful local currencies become as alternatives.
Explore the gift economy. Give away things you don't need. Get free things you do need. (This also minizes your landfill footprint.) Services such as Freecycle help people connect. See my article "The Richness of Giving."
Live in community. This lets you take advantage of economies of scale, and also means you can share big equipment such as a washer/dryer, lawnmower, or car. If you're a serious egalitarian, there are even a few communities that do income-sharing. But there are also neighborhood communities, cohousing, shared households, and many other options for people with all different kinds of lifestyle tastes. See my article "Householding: Communal Living on a Small Scale."
Choose alternative transportation to reduce or eliminate your dependence on car travel. This is good for the Earth, and reduces money flowing to the fossil fuel industry. Use public transportation, bike, or walk. Study the walkability of your community. If you really need a car sometimes, check out car-sharing organizations such as ZipCar.
Support green energy. Clean, renewable energy tends to produce more jobs than conventional fossil fuels. It shrinks your environmental footprint and draws money away from fossil fuel barons. It can also provide independent power for you. Search for green jobs.
Boost the signal! If you can't do anything else, at least lend your support via word of mouth. Help folks understand that they have options, and they aren't stuck always giving money to people whose interests conflict with their own. Pick any topic on this list and blog or talk about it, or add your own suggestions for how to draw money and power away from Wall Street and back toward Main Street.