Our partners at MacUpdate are offering Versomatic 1.0 for US$29.99 (40% off, retail $49.99). Versomatic is a powerful extension to Mac OS X that catalogs and archives all file changes automatically in real-time without you even noticing. It then allows you to go back in time and view or restore any earlier version of a file instantly. Versomatic can even recover previously deleted files regardless of when they were deleted (unlike traditional undelete utilities that only work well soon after the deletion takes place).