Data source(s) for mobile application - where/how can I find a resource?

I'm looking for a or multiple sources of data aggregation - specifically, I have a need to map/link a query to business within a specific geographic area, ala, yelp query. My question is how does or where does one go to query a locational based data set for business/entities within a geographic location. Let me give an example, say you're looking for a bookstore in the Pasadena area - what sort of data sets exist that can be queried, say google, yelp, bing, that will produce a JSON/XML data set that can then be manipulated by the originating query.<p>I have a concept that is promotable, but I am not looking to create/produce/define a data repository that contains the source data, but leverage existing data sets and massage them into valid results for the end users experience.<p>Leads, idea, method/source would be appreciated. I know/understand that this has been done - so I'm not looking to reinvent the wheel - I just don't know where to query to provide the necessary results sets to the application.<p>I'd appreciate any feedback, discussion, etc. that could shed light upon this issue I've yet to figure a solution for.<p>Cheers !