As many of you may have seen, festivals have already started dropping names for their 2013 editions. For many festivals, you can vote for your favourite artists. The organisation will then try to book them. I'd like to use this topic to collect all the (relevant) festivals for which this is possible, so we can all vote for The Sounds! I'll try to make a list of festivals in this post. Feel free to add more in the replies, preferably with a description how to vote (especially if the site isn't available in English). Let's do this!

Pinkpop (Landgraaf, The Netherlands, 14/15/16 June 2013)
http://www.pinkpop.nl/goudentip/
How to vote: Cast your vote by entering three (different!) artists in the first three lines. Then enter your name and lastly, your email address. Then press "Verstuur je tips". You may receive a confirmation email. By voting, you will also be entered in a competition to win a pair of weekend tickets for the festival.
UPDATE: Voting has closed!

Pukkelpop (Hasselt, Belgium, 15/16/17 August 2013)
http://www.pukkelpop.be/en/ (see "List time" on the right of the home page)
How to vote: Cast your vote by filling in five artists, click "next step" and enter your details. Click "send" and you're done! You may receive a confirmation email. By the way, you can only win a Pukkelpop sticker if you live in Belgium (bummer, hahaha).

Vans Warped Tour Europe (Europe, fall 2013)
http://www.vanswarpedtoureurope.com/
How to vote: Just fill in the following survey! You can choose five of your favourite bands and three of your favourite European cities. https://www.surveymonkey.com/s/Q3LTWSG

Any more suggestions? :)