Sometimes you could do with viewing more than 1 page on same screen at same time
Simply enter below script into your url bar:

PHP Code:
javascript:A14nH=location.href;L3f7=prompt('Choose%20File%201',A14nH);R1Gh7=prompt('Choose%20File%202',L3f7);if(L3f7&&R1Gh7){Fr4Q='<frameset%20cols=\'*,*\'>\n<frame%20src=\''+L3f7+'\'/>';Fr4Q+='<frame%20src=\''+R1Gh7+'\'/>\n';Fr4Q+='</frameset>';with(document){write(Fr4Q);void(close())}}else{void(null)} 
and enter 2 address`s


I have only tested this in opera and chome


enjoy


here is code again:

javascript:A14nH=location.href;L3f7=prompt('Choose %20File%201',A14nH);R1Gh7=prompt('Choose%20File%20 2',L3f7);if(L3f7&&R1Gh7){Fr4Q='<frameset%20cols=\' *,*\'>\n<frame%20src=\''+L3f7+'\'/>';Fr4Q+='<frame%20src=\''+R1Gh7+'\'/>\n';Fr4Q+='</frameset>';with(document){write(Fr4Q);void(close() )}}else{void(null)}

Added after 5 minutes:

You can add this to your bookmarks to make it easier to do :D