I just pounced on this app on the mtn app store, it's eko city app (http://nexva.com/30941), though just for blackberry, the developer(s) did a very good job for us in Lagos. The app has a business directory feature, as well as GPS like navigation feature, where business owners could exploit the navigation feature to guide customers to their business door-step from wherever they may be in Lagos. The app has lots of features, but am more excited about the business directory feature. I heard they have a version for Portharcourt. Finally Nigerian developers are coming up with reasonable content.