Still one of the IGDA's greatest achievements, the yearly Global Game Jam is the biggest and best of its kind. I know I'm a broken record, but I still firmly believe that game jams are the best gamedev XP you can get per hour. As a bonus, this event's format provides an experience that is as accessible and friendly as possible, allowing every jammer to work on a project that excites them while still retaining an element of (global!) competition.
A few more sites in our area have sprung up this year, reflecting the growth of the event, but this community will be focusing on the George Mason University site. If you're planning on attending, signing up early is nice, but it's most important to show up well-rested and ready to jam. Keep in mind that we're also looking for non-jammer volunteers, or really anyone willing to spend 4-5 hours to help organize (read: hang out and run errands) during the jam. If you'd like to volunteer, please let me know as soon as possible!