As usual, the PHP Usergroup Dortmund, in cooperation with people from Cologne, organizes a PHP room with talks and hacking. If you've never been to FrOSCon, you should really seize the chance. If you have been to FrOSCon, yet, you know what you would be missing! The call for papers for the PHP room is still open until May 23rd, so take your heels and propose some interesting talks for the PHP room.
This year's FrOSCon will be happening August 21st and 22nd and topics they're interested in this year include development, security, desktop and NoSQL.