*Compendium of Physical Activities - MySQL format
This list of activities and their associated MET values was compiled by the University of Arizona. You can find out more information on their website:
https://sites.google.com/site/compendiumofphysicalactivities/home
It is available in Excel format upon request. I took that Excel file and converted it to MySQL database so it could be accessed programatically. I use it in the ActivityCalc project ( http://activitycalc.com ).
This list was last updated in 2011. Check the compendium for updates as well as licensing information. Their website also contains a lot of other information about MET values and formulas for various unit conversions.