1. Mobile Device Management for all platforms2. Core System & System Optimization3. Camera Customization and Photo filtering by GPUImage or so.4. Google Map & Geolocation & GPS5. Web APIs & Parser & Backend Mobile App6. Social Network such as Facebook, Twitter, Google+, Thumblr, LinkedIn, Instagram.Building social networking apps, especially social photo sharing apps like Instagram or Path.Note: Developing web-service using php/mysql is no challenging to me.7. Video/Audio Streaming8. Advertisement service such as admob, adwhirl, iAd, ..9. Analytical service such as Google Analytic, Flurry.10. Push Notification and IAP for iphone & android & blackberry & Urban Airship.11. QR Code & Bar Code by ZBarSDK, ZXing, RedLaser12. Inverted QR Code12. Basic Photoshop skills13. 2D Game Development with fantastic design.Cocos2D, Box2D, Corona, Game Center, Open faint14 iPhone 5 and iOS6 change, new iPad Mini.