[nborwankar]

Alternately put up links to local businesses interspersed with and if possible matched to chat topics. Count the click throughs and email a weekly report to businesses if the numbers are significant. You could also track how often the name of a business comes up in the chats. But this may take a few months to bear fruit. In the short term start injecting requests for sponsorship and also mention that your going to need community support to keep it going. Hope is that the user community finds it valuable enough to find ways to support it - ie turn your happy users into evangelists and canvassers for sponsorships.