Our mashup Buy-Sell has been updated. It lets you match 'buy' and 'sell' tweets. It's sort of like a Craigslist for Twitter. This mashup connects Buyers And Sellers On Twitter.
Mashup supports geo search. So you can see related tweets for the specified area only. Just use latitude and longitude as parameters to the original URL:
lat – latitude
lng – longitude
For example, buying and selling in:
Mashup lets you see "buy-and-sell" tweets with photos. Also you can directly pass your search string to the basic URL. Parameter's name is q. For example: iPad
P.S. see also Tweet vs. Tweet mashup