Feeling Guilty About Global Warming? Not While You're Flying.

Travelocity and Expedia recently released services allowing travelers to make a tax-deductible donation to The Conservation Fund, a nonprofit that then plants trees.  The carbon dioxide released by the trees offsets the fuel emissions given off as a result of your flight and rental car use.  For example, a ten-dollar donation can make a two-trip "carbon zero".  This service is just starting, but is expected to take off very quickly.