I am using a 24" very bright monitor at work and realized it can be quite straining seeing too much white (actually it might be because of me coding with black background by now). So in order to make it easier for me to read texts one small bit at a time I wrote a small bookmarklet to cover the rest of the page with black (for IE) or black transparent (for browsers) areas. I also add a small link on the top to show and hide the blinds if needed.

Installation is as easy as dragging a link to your links toolbar. Check out the blog post about the bookmarklet:

www.wait-till-i.com/2008/09/24/reading-blinds-a-bookmarklet-to-help-me-read-easier/