A free app for Android, by sameh shafey.
iTop is a social networking application for iPhone that allows you to buy and sell anything online, including mobile phones, mobile accessories, and even land. You can do it all through the app, which has its own marketplace.
How does it work?
You can add anything you want to sell, like your mobile phone, tablet, or other mobile accessory. You can also add any product you want to buy, like a new iPhone, iPad, iPod, or other device.
The marketplace is where you can find buyers and sellers. Buyers can add a request for a particular product or service. If the seller responds with a price and product information, they can accept or reject your request.
You can also add comments to posts, and your followers can like or dislike comments and posts.
