Harold Washington Public Library online, Learn about Chicago 24/7
http://www.chipublib.org/004chicago/004chicago.html

The Chicagoland Information Portal for federal, state and City services
http://www.chicagoinfo.gov/index.html

Chicago Office of tourism
http://egov.cityofchicago.org/city/webportal/portalEntityHomeAction.do?entityName=Tourism

Wikipedia Chicago. Best link for chicago history, statistics, etc.
http://en.wikipedia.org/wiki/Chicago

Things to do, dining delights, Chicago's Exhibitor Corner.......
http://www.meetinchicago.com/

Chicago transit authority
http://www.transitchicago.com/

Chicago History
http://www.encyclopedia.chicagohistory.org/