Classified is a very popular service and from Craiglist to Olx to Quickr, it has evolved over a period of time. We have executed prototyping for a leading classified services which is very popular in middle east. It was fun to work out the nuances of the user/advert interaction. We did the complete prototyping for the app, web portal and also some documentation level work. If you have any creative ideas brewing around classified then do get in touch.