Ideally, the most legible typography contains between 45 and 75 characters per line. This is difficult to accomplish for all screen widths with only CSS media-queries. FlowType.JS eases this difficulty by changing the font-size—and subsequently the line-height—based on a specific element’s width. This allows for a perfect character count per line at any screen width.

Seems like an interesting script if you wanna fine tune that blog of yours. I need to try it out.