chicago.metromix.com -Connected to The Chicago Tribune, Red Eye, and has the top Google Search Results in the category.
chicagosportandsocialclub.com -Their niche is local sports leagues & taking pictures in bars to connect with people on facebook through tagging photos.
Meetup.com -This site is entirely user generated.
Going.com -Set up as a social network that allows venues to connect with people like friends do on facebook.
Free things to do in chicago – This is basically a daily deals type site, but more innovative because it only displays free events in Chicago.
Groupon.com – This looks like a daily deal site, but it is actually based off of collective action. If enough people agree to patronize a vendor all at once on a particular day, then the vendor offers a deal they would not offer otherwise.
Thelocaltourist.com -This is a full calendar and database focused on categorizing and reporting on neighborhoods in Chicago.
Chicago.citysearch.com – Just a general Calendar for the city set up through a search engine, but no niche.
Visitchicagoland.com -This seems to be meant for tourists.
Chicagokids.com – A Things To Do site for kids in Chicago.