The Apple brand is synonymous with good design. It also seems that a lot of applications made for Macs and the iPhone seem to possess a little something extra when it comes to aesthetics. The designers of these apps do a great job in carrying over that same high level of quality in branding. This is evident in the applications themselves as well as their websites. Most of these sites all share certain qualities such as excellent use of color, big highly detailed icons, and pixel perfect buttons.
Here's some other articles that you will definitely find useful.