EUROPA stamps are special stamps issued by European postal administrations/enterprises and bears the official EUROPA logo, started back in 1956.
Every year PostEurop hold the EUROPA Stamp Competition. This is an online event where everyone can vote for their favourite design (there is also a Jury competition in which the best design is choses by philatelic experts). The theme for the competition this year is Music. You can see the 2014 stamps and vote here. You have until 31 August to vote.
More information about the competition and past years stamps.