Beyond the fried Oreos, the fair's booths & exhibits are a great way to connect with the community. If you've been looking to start volunteering, you'll find representatives from dozens of groups happy to talk to you about opportunities. My friend Jan-Michael tweets that you can look out for The Green Miles featured on the Arlington County Fair poster with some friends from the Arlington Community Volunteer Network.
There are shuttles to the fair running every 30 minutes from the Ballston Metro, the Arlington Career Center, and the I-66 parking garage. But (assuming it's not 100 degrees) the fair's location at the geographic center of the county makes it a surprisingly decent walk from many parts of Arlington. It's an especially good idea for those of us planning on downing one if not several orders of fried Oreos. (Note: If there are fried Oreos to be found year-round in the DC area, please do not tell me about them. Regular access to fried Oreos would mean certain death.)
Finally, you can check out my photo-blog of the 2008 fair from the now-defunct What's Up Arlington.