I'm needing an iphone app, or possibly a web app, where a community of friends (100+ people) can list items for sale with pictures uploaded from their phones. The items are similar, such as bicycle parts. So the ads should be listed in categories by brand, and type... such as Brands= Schwinn Trek Giant Haro and sub categories such as... Handlebars pedals tires frames etc. I'd like it open to lots of people to be able to post their items with a simple registration. the ad listings should be able to show up to 4 pictures, with a description box. Pinch and zoom would be very helpful for the pictures. Im pretty open to any design as long as these functions are available.
I should add that it would be ok if everyone used the some login key, so each person doesn't need their own account, basically everyone can share the same selling account.