I’m really into super simple applications that rely on intuitive visual clues to convey information. Using color to represent the weather, as in this iPhone app, really sets a mood along with providing weather information.
Another great example of intuitive design is the popular Clear To-Do list app. I don’t actually use Clear on a regular basis (I’m more of an Omnifocus guy), but I really appreciate simplistic design aesthetic. I’m not alone, either. Clear entered a market heavily saturated with To-Do applications, charged $2.99, and still made a huge impression.
Anyway, this weather app is beautiful.