Making a difference in the world is commendable. Finding a way to make it a profitable business is just plain impressive. These 6 entrepreneurs have all achieved this. Find out what they are doing and why they are successful here!

Business Week shares…

For Profit, for Good

Earlier this year, we asked readers to tell us about entrepreneurs building promising businesses that tackle social ills. Over the past few months, we narrowed the more than 300 suggestions we received to 25 for-profit social enterprises. Among our criteria: scope, impact, and the ability to sustain themselves.

Amethyst Technologies

Baltimore; 25 employees; $1.8 million in 2011 revenue

Amethyst Technologies helps drugmakers and other health-care businesses in the U.S. and Africa comply with U.S. Food & Drug Administration and international standards. Among its work: assisting the U.S. military in developing malaria diagnostics and vaccines, and setting up labs in remote places such as rural Tanzania. Amethyst is also developing mobile software to help train rural health workers in developing countries. “Everywhere that Amethyst does work we should be benefiting the community,” says founder Kimberly Brown.

Carbon Lighthouse

San Francisco; 5 employees; $200,000 in 2011 revenue

Carbon Lighthouse helps offices, factories, and schools cut their energy bills. The company’s engineers collect data on temperatures, air flow, electricity use, and other conditions, then make small tweaks in building operations to increase efficiency. The company targets midsize buildings, between 25,000 and 200,000 square feet, and buys carbon offsets to make clients’ buildings net-zero emitters—a marketing benefit that often outweighs the savings. “It’s not all that sexy to talk about your very clever pump algorithm or what you’re doing with air dampers,” says co-founder Brenden Millstein. “Being net-zero carbon is very cool.”

Frogtek

New York; 30 employees; $200,000 in 2011 revenue

Frogtek sells inexpensive mobile software to shopkeepers in Mexico, Colombia, and Spain that connects to their mobile phones and allows them to accept credit-card payments and do inventory management. The company profits by selling data about its software users to food companies and banks. Founder David Del Ser earns a fraction of what his former MBA classmates make, but says his payoff comes in the excitement he sees on new clients’ faces: “I knew mobile phone technology could be put to work to help these small entrepreneurs prosper.”

Green Dot

Cottonwood Falls, Kan.; 7 employees; no revenue in 2011

Green Dot is developing a compostable, biodegradable soft plastic based on cornstarch to replace petroleum-based plastics. The company has shipped nearly 70,000 units of its first product, an iPhone case sold online and through outdoor goods retailer REI, and expects more than $1 million in revenue this year. The cost of the bioplastic, at $4.50 per pound, is competitive with similar materials that aren’t biodegradable. “It doesn’t go in the landfill. It’s toxin-free,” says spokesman Kevin Ireland. “We’re trying to decrease the amount of enduring waste in the environment.”

Harvest Power

Waltham, Mass.; 395 employees; $35 million in 2011 revenue

Harvest Power processes food scraps, yard trimmings, and other organic materials to extract natural gas and produce fertilizers, mulches, and soils it sells to landscapers, homeowners, and farmers. With 25 facilities, Harvest Power gets paid by municipalities and businesses to repurpose more than 2 million tons of material annually. That’s a fraction of the 500 million tons of recyclable organics produced annually, but it’s a start. “This is a major, major source of renewable energy and most people don’t grasp its potential,” says Chief Executive Officer Paul Sellew.

Get the entire article at Business Week!

Do You Own Gold?

Gold prices have been bouncing all over the place for the past few months, but investors have no idea what is coming next? In this new free report, RC Peck, discusses exactly how to invest in gold safely, how to simplify your investments, and how to align yourself with the oldest type of gold company in the world...

If You Own Gold, or Would Like To Profit From Gold, This Report Is For You