http://web.dreamhack.se/index.php?language=en&section=1

What is DreamHack?
DreamHack is the world's largest LAN-party, demoparty and computer festival! Last winter we checked in 10,638 people!!
DreamHack is focused on everything you can do with computers: a lot of gaming and communication. Programming, designing, music composing and whatever you can imagine! We organize a lot of large game tournaments.
DreamHack is filled with activities and surprises.