X-Mouse Button Control is a free Windows application to reconfigure your mouse buttons and expand the capabilities of your mouse!

You are able to provide application or window specific mappings, which means an application or window can use the mouse buttons differently from another. For each profile you can optionally define up to 5 'layers' of different button configurations which you can switch between using hotkeys or mouse buttons.

You can also alter the behaviour of the scroll and tilt wheel functions, fixing windows that don't normally respond to these controls.

Profiles are automatically activated by moving the mouse over the defined window or alternatively, when the specified application is active. This has many uses, for example:
In games which do not natively support the extended mouse buttons, you can map keys to each button.
Changing the behaviour of the mouse over certain windows, such as making the mouse wheel change volume when hovering over the system tray.