I have spent time on some of these sites and also tried Muzli. If a bigger part of inspiration is to solve a UI problem in hand, I'll recommend http://collectui

I have spent time on some of these sites and also tried Muzli. If a bigger part of inspiration is to solve a UI problem in hand, I'll recommend http://collectui.com/ http://collectui.com/. They give you a well categorised collection of working UI done by different companies / products.