Until today 17.00 CET [BT] you can vote on this page on the Spanish-Belgian-Hungarian Troika logo. The page is Hungarian, but it is quite clear what to do:
Chose your favourite logo, scroll down, chose the right number, and then vote!
PS.: I opt for the first logo, because it's the only one that combines both national and European colours without being too abstract.
(via + via Daniel Antal)