I'm a member of Pumping Station: One, and there's a lot going on there, including Arduino fun. Thursday nights are Transistor Thursdays, when we get our Arduino on. The guy who runs it is out of town, but the next one is October 8th, 7pm. 3354 N Elston, come on out!
And if you wanna integrate your Arduino with, say, an item of clothing, or something made out of wood or cast from aluminum, or whatever, we can help you with that too. Lots of fun toys.