Updated November 2011 and February 2013 In a simliar to my posts about Linux and Windows here are the things I add to a Mac
  1. Homebrew (but only for the geeky)
  2. Chrome
  3. Thunderbird email and calendar client
  4. Adium, messaging across all the IM networks
  5. Skype, the worlds most popular VOIP client (but closed)
  6. Filezilla
  7. KeePassX password manager
  8. macvim, the worlds best editor
  9. Twitter
  10. LibreOffice
  11. smcFanControl, helps cool the hot metal on a Macbook
  12. UnRarX for the odd occasions when you need to unpack a RAR archive
  13. VMWare Fusion
  14. Quicksilver
  15. iTerm2
  16. SourceTree git and hg GUI client
  17. Caffeine
  18. Freeplane to edit mind maps
  19. GNUcash
I've also bought iTaskX for project management and MS Office 2011 as I need compatability with MS Office 2010 document formats :-(