Download the State of the Internet presentation from Google Docs.
Do you know if the results you got in your A-B split tests are statistically valid? Based on information from Marketing Experiments I have converted some of the standard equations into a spreadsheet.
Simply plug in your numbers for clicks and impressions and the spreadsheet should let you know whether you have a valid test using a few different equations.
To access this spreadsheet go to http://spreadsheets.google.com/ccc?key=rlurFcb173_TH513DHmylyA (opens in a new window).
Mega Drop Down Menus