Our company organizes a monthly conference about game development. Like the others said, it's a great way to meet with fellow developers and chat about almost everything - from software architecture to gaming, with a beer at your hand.
Also, after every conference, I feel so inspired and motivated. It's like I recharged my batteries to 100%. Another big benefit of attending conferences is the in-deep material you are presented. For example, 3 days ago, Na'Tosha Bard, the Technical Director for R&D at Unity Technologie came to our meeting and gave a presentation about the development processes inside Unity. We had a chance to chat with her and ask her questions about testing and deployment at Unity. Some of the things she shared with us, we are going to implement in our development process really soon.
Attending conferences is a great way to meet people with the same interests as you, make new friends and learn something new and I would advise everyone who hasn't gone to a conference to go as soon as possible!