The Q button on the back of Canon cameras is used primarily for quick access to the camera's primary settings.
If you're like me, and avoid manuals at all costs, you may have missed another function of the Q button, too. The other day, I discovered that while in the camera's menu, pressing the Q button moves to the next menu category.
Instead of rolling the wheel through several submenus in each category, just press the Q button until the menu you want is highlighted.
It would appear that this only works on Canon cameras that contain submenus. The 7D, for example, uses tabs instead of submenus, so the Q button doesn't help.