Mathias Nitzsche had a nifty idea: using Wi-Fi network names to create a connection between the network's owner and those who spot it in their wireless networks list. His aptly named wifis.org site lets you pick a handle and advertise it through your network name, as in wifis.org/glennocschmidt. This creates an account for you on the site, and makes a Web form available at that address that sends email to your Google or Facebook email, whichever you used to create the registration. The visitor never sees your email address. (Nitzsche avoids having his own registration database, which removes some overhead and security risk associated with retaining passwords.)
I contacted Mathias to ask about privacy and security issues, as one might be concerned about email addresses being stored and the association of a Wi-Fi network name with such. He said (and his FAQ notes) that he doesn't reveal information to third parties. While he's based in Germany, his data and application is hosted in the Google App Engine in the United States.
I'd love to see a variant on this idea, in which an existing network name could be paired with a unique few letter long code that someone would then append to their network. Look up the code, and you'd get the same result. I admit Nitzsche's idea is neater, encoding the URL and the identifier all at once.