I've had similar reactions from Project Managers after I showed them some versioned Excel files. They were blown away by the ability to go "back in time without having to manage copies". The revision graph totally floored them.<p>There's an opportunity here somewhere... take TortoiseSVN, remove all ability to branch/merge and anything beyond taking a file forward and backward in a timeline, make it stupidly simple and use words that non-technical people understand. And then sell it as the "time machine for files".<p>For recurring income, make it a DVCS (so start with TortoiseHG instead of TortoiseSVN) and offer to back up their files for $5/mo and make the "backup" a `hg push remote`<p>I'm telling you, it's amazing how few people who work with computers and digital files all day long have _no_ idea about cvs,svn,hg,git, etc.<p>They think that if it's not handled by the display application (Excel, Word, etc), it's not possible. They have no conception of doing stuff on the file level.