In no particular order:
Milwaukee Avenue Arts Festival in my neighborhood (Logan Square). Fri, Sat, Sun with kids activities
Halsted St Market Days - probably not kid friendly, unless your kid is into leather thongs... 
Fiesta del Sol in Pilsen
Open Streets - Saturday from 8:30am - 2pm bike about 8 miles of CAR-FREE roads from Logan Square down to Little Village. How awesome is that?
Free Museum Days - use your Bank of America card to get in free at these museums this weekend:
Art Institute of Chicago
Chicago History Museum
Museum of Contemporary Art (no Sundays)
Shedd Aquarium
Official Site: http://museums.bankofamerica.com/
Beach Tennis on the lakefront. Sort of like cross between volleyball and badminton.
Enjoy!
Thanks Mark - good to see
Thanks Mark - good to see you yesterday! By the way, "your child is crying sir"!! Can you believe that woman?
Chat soon!
Peter, Charlotte & Dorothy.
1 uncool thing to do
Car Seat Safety Check Sunday, August 2 From 12:00 p.m. to 3:00 p.m. on Sunday, August 2, families with young children will be able to have their car seat properly installed and/or inspected by a certified professional at the fire station at 6030 N. Clark St. in Edgewater. Sponsored by Representative Harry Osterman, the event also will feature music, refreshments and fun activities. Children will have a chance to tour the fire house and take a picture on a real fire truck, and adults will be automatically entered in a raffle to win a free car seat and other prizes.