20 Free Application To Increase Productivity

1. Launchy - free program launcher
2. AutoHotKey - automate just about anything by capturing your keystrokes and mouse clicks
3. AVG Anti Virus
   
4. Spybot Search And Destroy - anti spyware
5. Ad-Aware
   
6. Free Download Manager
7. BK ReplaceEm - powerful search and replace utilities, allowing you to operate on multiple files at once.
8. Google Web Accelerator - allow you to enjoy faster web browsing in seconds
9. CamStudio - recording software that will allow you to create demonstration videos, online tutorials, or even video-based information products
10. Audacity - software for recording and editing sounds. You can use Audacity to record live audio, edit sound files, mix sounds together, and much more
11. Foxit PDF Reader - fast PDF reader convertor etc
12. 7-zip - file compressor
13. CCleaner - removes unused files from your system, freeing up valuable hard disk space.
14. Openoffice.org - a replacement for Microsoft's Office Suite
15. Better Gmail -To enhance your Gmail for optimum productivity, then you will need to download the Better Gmail Firefox extension.
16. FileZilla - fast reliable FTP client
17. RoboForm - password manager and web form filler that will allow you to browse the Web faster than ever

I found only 17 to be useful. :) . Courtesy: Top 20 Free Applications to Increase Your Productivity