Windows Tool of the Century
Okay, maybe “century” is overblown, but the True X-Mouse Gizmo for Windows is the best thing since sliced bread (if you use Windows):
Have you ever paid attention to striking difference in the thickness of forefingers in X11/Unix and MS Windows users, respectively? The latter have much more muscular forefingers that often suffer from chronic aches in their joints. They also much more often develop mouse arm, pain in the neck and shoulders, and other troubles known as Repetitive Stress Syndrome and associated with excessive usage of a pointing device. Why?
The Gizmo even solves the classic X copy/paste buffer problem where you want to select text to paste the contents of your copy buffer over it, only to replace your copy buffer with the newly selected text. Linux could use such a solution, as well!