Your favorite Linux apps?

Today in Open Source: Share your favorite Linux apps. Plus: Switching from OS X to Linux, and switching from Windows 7 to Linux.

I always enjoy threads like these because they help new Linux users discover applications that they might otherwise never know about. There are so many fantastic applications available for Linux that it can be overwhelming to new users. So an app discovery thread like this can help guide people to some of the best applications out there for Linux.