Value of anonymized user trend data

I was wondering how to find out how much the user data is worth for a database similar to Foursquare's? I'm not looking to sell personal user information or email addresses, but more along the lines of:

"18 yr old males who visit Vietnamese restaurants once a month also goto the movies once a month"

"Females above 30 yrs old tend to eat out less than 4 times a month"

"Coffee restaurants in the core of Toronto tend to have more tech-savvy visitors on the weekends"

I recently talked to an angel investor about my company and he mentioned that this is the best way to make money in this space (location based services), but I'm having a lot of trouble learning about what data is relevant, has the greatest monetary value, and what exactly is legal/illegal (In Canada & the US)?

Is there a specific name for the industry of selling/buying "trend data". Are there specific companies that would buy this type of data? Is it typical for web-based or customer loyalty companies to sell this data, and if so, is this a main source of revenue?

Thanks in advance!

A logical customer for your data would be existing market research firms.

Get in touch with some people working in these operations. (Via networking, LinkedIn, cold contacts, whatever). Chat with them to get a feel for how much your data is worth. They can also tell you how they currently collect such data and who your competition is.

A starting point: check out the firms buying ads for the Google terms "market research".