two words... blizzard authenticator.
if you can get an authenticator or have an iphone application. ( not sure if other phones can do it ).
I made 5 battlenet accounts and assigned a wow to each so I can do 5 logons at once, if you have all of your accounts on one battlenet account then you will have to logon one at a time (which sux since you have to wait for a new number for each logon ).