From Debit to Credit Turn the tables on business costs and look for creative ways to eke out a little revenue.

Small-business owners constantly seek ways to rein in expenses, but truly savvy entrepreneurs look for opportunities to turn those expenses into income.

Some examples are straightforward. By subletting unused office or warehouse space, for example, you can convert a rent bill into a check. Other opportunities require more legwork. Instead of paying a waste disposal company to haul away the boxes your suppliers send your way, what about selling them to an organization that needs boxes to ship products? It can get a discounted price from new, and you can add a few more dollars to your bottom line. (Recycling other materials can turn trash into treasure as well.)

David Price, director of sales and marketing at SportsWorkout.com, in Columbus, Ohio, and Chicago, says his company used to pay a third party several hundred dollars each month to send out its newsletter, which provides content and product information to customers. He since has switched to a free newsletter service and started selling ads to suppliers and other organizations that want to reach his customer base. "We went from spending over $200 per month to send our newsletter to making $150 or more each month on advertising," he says.