We introduce MobiAd; a scalable, location-aware, personalised and private advertising system for mobile platforms. Advertising is the driving force behind many websites and service providers on the Internet. With the ever-increasing number of smart phones, there is a fertile market for personalised and localised advertising. They key benefit of using mobile phones is to take advantage of the vast amount of information on the phones and the locations of interest to the user in order to provide personalised ads. Preservation of user privacy is however essential for successful deployment of such a system. MobiAd would perform a range of data mining tasks in order to maintain an interest profile on the user's phone, and use the infrastructure network to download and display relevant ads and reports the clicks via a Delay Tolerant Networking (DTN) protocol. In this paper we provide an overview into existing advertising systems and privacy concerns on mobile phones, in addition to the scalable local ad download and privacy-aware DTN-based click report dissemination methods that we propose for MobiAd.