Although this webpage isn't reallf long, I think it is simple and imformative about what alingment is. It also discusses the use of grids in graphic designs and it also explains the types of text alignments that are discussed in the book. Overall this website is short, simple and sweet but helpful.
This website deals primarily with the concept of the visual hierarchy and goes into great detail how it is used to emphasize various aspects of a website or layout.
Ch 7-BoD Flow
This site illustrates the concept of visual movement of flow in web design. The picture shown on the page provides hands-on examples of visual elements through text blocks which create "flow."