Today is Earth Day and the search industry is sporting special logos for the day. Here is a run down for the 2008 logos:

Google:

Yahoo (Flash version):

AOL:

Ask.com:

Cre8asite Forums:

Search Engine Roundtable (our theme, it actually glows):

Past earth day themes and logos from the search industry:

Google, Ask.com & Yahoo! Earth Day Logos, 2007
Search Engine Commemorate Earth Day 2006, 2006
Ask Jeeves & Google Earth Day, 2005
Google Commemorates Earth Day, 2004

Forum discussion at Search Engine Roundtable Forums