Designing a site is not as easy as some might think. Today it iseven harder because the designer has to keep in mind the different media devices their site will be displayed on. In the past this means creating different images, different styles, and in essence a different site.
I stumbled upon a great site Font Awesome and they took icons and converted them into vector based fonts. Changing colors and more importantly icon scaling really is awesome. And if you are using Twitter Bootstrap they document how easy it is to integrate.