ClickForMe

Avoid mouse button clicks by letting your computer do it for you!
ClickForMe will automatically issue a mouse button click when the mouse cursor is held steady.

Choose from automatic left, right, center, double, and triple clicks. Also supports dragging.
Works seamlessly with all programs on Mac OS X.
Supports Mac OS X Snow Leopard 10.6, Lion 10.7, and Mountain Lion 10.8.