I thought the two following articles interesting. Please note, the best beaches are mostly all protected by the government of their perspective country.
World's Best Eco-friendly Beaches
http://edition.cnn.com/2010/TRAVEL/07/17/ecofriendly.beaches/index.html?hpt=C2&f bid=-Bts0kZ-3ZT
15 Travel Destinations Being Ruined by Tourism
http://www.mnn.com/lifestyle/eco-tourism/photos/15-travel-destinations-being-rui ned-by-tourism/treading-lightly