National Geographic
Make sure you've got some time to kill before diving into National Geographic's Web world, as you can easily pass hours digging into the depths of the global ecosystem and other eco-weighty subjects that other sites merely skim. From stunning collections of nature photography to in-depth sections on topical environmental issues such as dwindling freshwater supplies and the prospects for renewable energy, National Geographic runs the gamut of nature's wonders — and biggest threats. What's more, it backs it all up with an impressive array of interactive maps and games. Feeling chained to your desk? Let the site's field reports transport you from a New York City office tower or a back office in Bentonville, Ark., to a wave-riding research vessel scouring the Mediterranean Sea. Just don't blame us if you miss the 3 p.m. meeting with your marketing team. (See National Geographic's mobile app.)