Back button on the mouse? It will be helpful for browsing.
It probably depends on the mouse you have, and any software that will let you modify the various buttons.
On the other hand, if you press Command and then the left or right arrow keys, you can move forward/back with your browser.
Cmd+[ is default for back. I'm sure there is a way to set the right click as back and I will look for it until someone with more knowledge comes along.