Got a few things you’re looking to offload on Craigs’ List for some last-minute holiday cash, or perhaps you’re still combing the online ads in search of that special Christmas gift? The EggDrop mobile app accommodates that by making it easy to sell a product online, real-time message questions about it and do price haggling over it, and check buyer and seller reputations. But its leveraging of geotagging and open data also can promote a smarter and someday, perhaps, more discovery-oriented and meaning-rich neighborhood marketplaces.

The idea behind the service, which is backed by an SV Angel, BlueRun VenturesTrinity Ventures, and Charles River Ventures, is to take the friction out of online selling and buying for individuals. Sellers can take their Android or iOS mobile device, snap a picture of what they’re trying to sell, name and describe it, and use its added functionality to with one click post the item via Facebook, Twitter, Yahoo, Google groups and Craigslist.  The neighborhood angle is that every item listed is geotagged using the smart phones’ location services, so that users are able to search on items that are close to where they are.

“Geotagging is kind of interesting in that we’re experimenting with what we call serendipitous discovery,” says co-founder and CEO Dan Zheng. “Imagine that you combine geotagging and real-time notification, with some personalization and recommendations on the back end.” The idea is to let users looking for a particular item – a collectible, perhaps – add it to a wish list, and get a real-time alert if the item shows up where their mobile device indicates them to be, including far from home base. Most people traveling out of town wouldn’t necessarily be combing online sales sites for goods as part of their trip, but this way if the item shows up within a certain distance of their current locale, they’d learn about it without having to lift a finger.

Additionally, the service also is integrating other sources of location data, such as General Transit Feed Specification (GTFS) data. Using that public transportation data, it can add additional meaning to location information to help users plan their trips to acquire an item, such as indicating that it  is located near a certain New York City train stop. Zheng says adding more metadata to item listings also could lend itself to aggregating and analyzing buying and selling trends in different areas of the country or in its international markets. “That could be really interesting data for a number of purposes,” he says. Potentially that could feed into ideas the company has about driving revenue for its service from various sources, such as offering value-added services for subsets of sellers and becoming the transaction buying and selling platform for local businesses.