The cookies used on this site are as follows:

__utma 2 years from set/update Used to distinguish users and sessions. The cookie is created when the javascript library executes and no existing __utma cookies exists. The cookie is updated every time data is sent to Google Analytics.
__utmt 10 minutes Used to throttle request rate.
__utmb 30 mins from set/update The cookie is updated every time data is sent to Google Analytics.
__utmc End of browser session Historically, this cookie operated in conjunction with the __utmb cookie to determine whether the user was in a new visit.
__utmz 6 months from set/update Stores the traffic source or campaign that explains how the user reached your site. The cookie is created when the javascript library executes and is updated every time data is sent to Google Analytics.