Earth Day 2010 has come and gone, but many companies are pursuing new environmentally sustainable initiatives all year long. Let's look at several interesting recent green developments from the last month that merit investors' attention.

Back to school, forward to green
Many companies are offering sustainable wares for this year's pivotal back-to-school shopping season. Brands and retailers are desperate to lure consumers and their dollars this year; the back-to-school market represents $55 billion in sales overall.

In this fiercely contested market, green products may provide a major competitive edge. According to USA TODAY, some tiny suppliers are offering biodegradable school supplies such as rulers and pencil cases this back-to-school shopping season. On a larger scale, well-known brand PaperMate now sells biodegradable pens through retailers such as Office Depot, Sears (Nasdaq: SHLD), and Amazon.com (Nasdaq: AMZN). It also offers pens and pencils that are mostly or entirely composed of recycled materials.

In the realm of apparel, skate and surf brand Volcom (Nasdaq: VLCM) offers sustainable clothing for eco-conscious teen shoppers. Its Volcom V.Co-Logical series uses "100% certified organic cotton, hemp, vegetable dyes, organic stains and other low impact production methods." Furthermore, 1% of the V.Co-Logical series' sales are donated to environmental causes.

Future back-to-school shopping trips may make it easier for eco-minded consumers to gauge the sustainability of the products they're browsing. According to The Wall Street Journal, about 100 major retailers and apparel brands are teaming up to create The Eco Index, which will measure the environmental impact of their wares, and allow them to put an "eco-value" label on their packages.

Brands included in this environmentally minded coalition include Target, Nike (NYSE: NKE), Levi Strauss, Timberland, and Patagonia.

Strange bedfellows
Hades must be going through a cold snap: Seventh Generation's eco-friendly cleaning products will now be available through Wal-Mart (NYSE: WMT). According to a Wall Street Journal report, Seventh Generation co-founder Jeffrey Hollender said years ago that "hell would freeze over" before that ever happened. (Seventh Generation already sells through many other stores, including Target and Whole Foods Market (Nasdaq: WFMI).)

Years later, it looks like Hollender and Seventh Generation have accepted what some environmentalists and environmentally minded companies already have: Wal-Mart can reach massive numbers of consumers on a global scale. If you want to see some real change -- and significant sales of your eco-friendly products -- embrace Wal-Mart. (The megaretailer has also worked on sustainability initiatives in recent years, including a sustainable product index.)

Honest Tea, another eco-friendly brand that enjoyed initial success through Whole Foods Market distribution, has found a strange bedfellow of its own. The organic juice and tea purveyor, which generated $47 million in sales last year, is currently 40% owned by soda behemoth Coca-Cola (NYSE: KO). The WSJ reported that next year, Coke has the option to buy the entire company, a development that the soft-drink giant says it's considering.

These pairings may not be so odd after all. If more and more consumers are seeking brands and companies whose businesses exemplify social responsibility, trust, and positive purpose, then corporations must work hard to woo them.

What's next?
Sustainable initiatives not only make the world a cleaner, less wasteful place, but often help companies drive additional revenue, save money, or devise better operational processes. Given consumers' growing interest in sustainable living, companies that source their power or otherwise conduct business in eco-friendly ways could enjoy a significant boost to their public image. In the long run, that could benefit their shareholders as well.

Have you noticed any interesting green innovations among publicly traded companies? Want to call a company out for lame, half-hearted efforts to "greenwash" its image? Sound off in the comment box below.

Coca-Cola and Wal-Mart are Motley Fool Inside Value selections. Amazon.com and Whole Foods Market are Motley Fool Stock Advisor picks. Volcom is a Motley Fool Hidden Gems choice. Coca-Cola is a Motley Fool Income Investor recommendation. The Fool owns shares of Coca-Cola and Volcom. Try any of our Foolish newsletters free for 30 days.

Alyce Lomax owns shares of Whole Foods Market. The Fool has a disclosure policy.