There are a number of other site clones -
http://www.redhotpawn.com
http://www.redhotchess.com
http://www.timeforchess.com
http://www.chessatwork.com
[see the FAQ]
Either get another browser - Opera, Firefox etc or each use a different flavour of the site. Even if you use separate browsers it's probably best to use different site instances when you share a PC (makes less chance for 'accidents' with each others accounts).