I say not to add them... why?
Apply the Do you really need it rule. Do you really need back links? Can you still get around without backlinks! Yup! --Wim
I've been thinking of refactoring this page into a more general thereom about duplicating functionality. Why implement a feature in the page if the browser already supports it? I don't know of any common or semi-common browser that does not have a Back button or a History feature. --Wim
See also MiniWiki