Google analytics has made it extremely to track and calculate marketing efficiency using the campaign tracking tool.
Google provides an Tool to generate the tracking url below
http://www.google.com/support/analytics/bin/answer.py?hl=en&answer=55578
I have generated a url
http://www.mywebexperience.com/?utm_source=gmail1account&utm_medium=email&utm_campaign=massmailingdecember
This url says that the source is gmail and medium of marketing is email and campaign name is massmailingdecember.
Once this url is make it can be masked using the standard html options to look like a simple link like this mywebexperience.com
This campaign can be tracked in Google analytics using the segment option available
People visited this page using Tracking Clicks in Emails and Web Pages Using Google Analytics Track email visits in analytics Track visitor source link in analytics