As is becoming custom, major sites tweak their logos or site designs to celebrate Earth Day.

Google does an excellent job, as always, at rolling out a stylized logo. When clicked on, it goes to an Earth Day search results page. Simple!

This Google Blog post details the latest steps the company is taking to help green up the environment. It's a little heavy on the Google webapps and such, but there it is.

Yahoo's logo transforms before your very eyes in a neat little animation. Click on it, and you're taken to the Yahoo! Green microsite. There, you'll run into their Free is Good promotion, a contest that promotes reuse groups like Freecycle, but on Yahoo's own network. One of the prizes is a Smart car.

MSN is a little more low-key, opting to skin their site in green tones. On the other hand, their green microsite is loaded with goods. Highlights include:

Encarta's Earth Day Page
Earth Day in the USA
"The Living Sea" Documentary Free Download

AOL's logo points to Green Daily. Some of the notable articles there are:

This or That: Black websites or white ones?
5 ways to start going green, if you haven't already
10 Green Gadgets You'll Love
6 Items You Didn't Know You Could Recycle

As you can see, there's no shortage of Earth Day content, and that's just at the major sites and portals. One interesting thing I've noticed this year is that the online community seems to have mellowed from the "Inconvenient Truth" hysteria, and instead, their starting to mobilize using the 'net.

And that's progress.

Update:  Digg has joined in with a tasteful little box that encourages its users to participate in their Environment category.