I came across this article today -- it's old (2007), but still thought provoking. Understanding Web Design.

The writer talks about how graphic & print designers often view website design as being so limited, with limited fonts, very specific grids, headers, footers, sidebars, etc, etc. However, he says we should look at web design from a different perspective. Web design is more like architecture or typography. His definition of web design is this:

Web design is the creation of digital environments that facilitate and encourage human activity; reflect or adapt to individual voices and content; and change gracefully over time while always retaining their identity.

I like this definition because it challenges me to think outside the box when I sit down to a build a design. It emphasizes how web design is really more of an interface, or an environment, rather than just a visual thing.