Style Switchers, from Smashing magazine.
Hmmm. The fact that a lot of users, especially windows users, see the Unison site with much larger fonts than I typically do when I am designing it. But not all. The browser can change font sizes, for those that know about it. But a style switcher would make it more explicit. This article shows you how.
Style switchers are used to provide users with a choice of layouts, fonts, colors and views they can use to adapt the design to their personal needs. Designs with style switchers are more flexbile, more adaptive and more user-friendly as different visitors can quickly modify the design for their personal convenience.