Raindrops on Roses and Whiskers on Kittens … plus related software and hardware.  This is a Mac/Apple bias list, but some, like 1 Password, may have versions for both platforms:

I consider the following items must have / must use:

• 1Password – password management software
• Time Machine – software included with Leopard+ for backing up files.
• Backblaze – on line backup service (if you have decent internet connection speed)
• Clips – “Use Clips to increase productivity during your daily computing experience. Try Clips today and enjoy clipboard management, the Mac way”
• Dropbox - file synchronization & sharing service.  Allows you to rebuild from previous versions and create easy photo galleries.