I am not talking games, but the 3 applications that you find yourself using the most when not playing games.
And, No, I am not talking about IE, or FireFox type programs.
For me it is:
1. YNAB (You Need A Budget), Pronounced Y-NAB. It helps you keep a great budget and has been a real eye opener for me personally.
2. MS Office - Use it all the time for work
3. BibleWorks 8 - Bible search program I use all the time. I use nearly as much as Office.