If the browser supports it you can use location.replace to replace the current page in the browsers history with another page - so that clicking back will skip the redirection page. It's good to add a location.href redirect for browsers that don't support it.
if (location.replace){ location.replace('/'); } else { location.href ='/'; }
Also beware of this IE location.replace bug http://splintor.wordpress.com/2007/04/12/locationreplace-and-back-button-bug-in-ie/