I've mentioned this before, but I have a spreadsheet on google docs to keep track of shaves on a blade. I use all of my razors, and keep all of them loaded and ready to shave, so the spread sheet keeps track of the madness. Only takes a few seconds a day to update and I can jot down my impressions of a particular razor/blade combo. Fairly "retentive", I know, but it works for me! :