Mandy Brown, a creative director at W.W Norton (& Co.!), wrote an article called "In Defense of Readers" for A List Apart, about webpage design:
Many sites scatter related content around the article, instead of focusing it at the top or bottom, where it’s more useful and less likely to be a distraction. If you want your users to skim the page, then by all means, fill the sidebar with content all the way down. But if you want them to read—if the page was written and not merely filled up, if the text consists of carefully crafted prose rather than bullet points—then respect the reading process and move that content elsewhere. The middle of an article should reflect the solitariness of reading with a design that neither interrupts the text nor the reader.
Related: via Kottke, something called arc90 Laboratory created this program called Readability. It basically strips away all the clutter surrounding the actual content on webpages. Their website has a better description, along with demonstrations and installation instructions.