In your local coffee shop, there are probably tons of interesting people around you--all using the free (or not so free) wifi.
Some of those people may be consultants for hire. Other people might be doing really cool startups. The guy next to you may be your best friend's new roommate. The girl across from you might be your soul mate.
How would you know?
How about an opt-in social network that you login to when you get sent to those Terms of Service pages for logging in to the free wifi. You could agree to show your profile--which could be a new profile or maybe just an aggregation of your Facebook, LinkedIn, etc profiles anytime you login to that wifi node.
Personally, I'd love to know who's around me when I'm sitting down at a coffee show and I'd be more than happy to display what I'm up to as well. Plus, I like the idea of making the coffee shop experience offline a lot more social, because you could start a conversation with someone in person based on mutual interests.
The data about where I tend to login to free wifi could also be used in a MyBlogLog kind of way... where if I login three times, I automatically get added to that shop's community. At that point, it would benefit the shop to provide free wifi and encourage participation on the network, because seeing where interesting people or your friends go to hangout would encourage you to show up as well.
Of course, this means you have to have feet on the ground to get into the firmware/software setup of all these routers in all these random coffee shops. There's no easy way to get viral adoption here. It's curious to me why Starbucks never setup the "Your Starbucks" social network, because people have such strong affinities to the one that they go to and often see the same people all the time.