Essential Software/Apps We Can't Live Without

List Rules
The computer & smartphone apps you use the most
The most essential software/apps, ranked by the wisdom of the crowd. Anyone can add their favorite software and apps to this list, making it an accurate, real-time ranking of the best software, as picked by the people who use these applications every day. Add your two cents, share your software expertise, and see how your app addictions stack up against everyone else's.
Ranked by