Z-Delicious Mobile Apps
HTML, Javscript, Android, IPhone and Windows Mobile Apps
Windows Phone 7 Apps
Windows 7 and 8 metro apps is an emerging market for app developers. The most favorable monetization model is freemium, which means publishing the app for free and including ads.
HTML5 Web Apps
Web apps are great for prototypes and MVPs (minimal viable product). They are easier to deploy to multiple platforms without too much code duplication. These days, there are many commercial grade HTML mobile frameworks and libraries for free that can utilized for development.