While there are some excellent mobile websites and apps, there are still plenty that fail to provide a good experience for mobile users, the Zara iPhone app being just one example of this

I’ve gathered together seven excellent presentations from Slideshare on the subject of mobile usability… 

Rethinking the mobile web by Yiibu

Development for the new mobile web

Tapworthy: Designing iPhone interfaces for delight and usability

Android UI design tips

Usability in mobile applications

Designing accessible user interfaces for mobile phones

Design Matters: A mobile UX manifesto