Google Drive and Revision History
Since 2005 when I purchased Microsoft Word for my MAC, my software was stolen when I mailed it to NYC. I was naive at the time, so I didn't insure my mail. In any case, I had purchased the CD for $199, and tried getting my license key and that version of software to no avail.
Fast forward to 2013. I had to create a UX Audit template, and miraculously was able to do everything on Google Drive, formerly Google Docs. My favorite feature is the Revision History, which came in handy when I had accidentally ported the wrong spreadsheet into a different file. In any case, I was able to undo several steps.