Most browsers: The article-saving, text-streamlining webapp Instapaper intentionally keeps its site dead simple to use. If you'd like just a bit of a colour and style upgrade, the Threestyled script, and its Greystyled counterpart, add a bit of polish.
Image via Digitizd.
Threestyled and Greystyled exist in tandem because Instapaper has upgrade some of its users to a newer, beta text engine, which breaks Threestyled's nifty folder/articles layout view and shading, rounding, and other tweaks. Greystyled works just fine on the newer Instapaper engine, but mostly adds just a touch of grey distinction to the article view. Threestyled, on the other hand, offers a bit of green colour, a Fluid-friendly stand-alone browser view, and other niceties. If you're going to read text in a browser, a little peripheral pleasantness can go a long way.
Threestyled and Greystyled are free downloads, and should work in Firefox with Greasemonkey, as a Chrome extension, or in other browsers that can apply user scripts.