In the interests of ease of reading, I've tried to use a consistent style of marking up different types of information on my pages. If your browser is capable of rendering CSS, then you can see an example of this on my styling template page. Other browsers shouldn't notice anything different than any other webpage (i.e. they'll see simple webpages, nothing special about them, and nothing special required to see them), but these are the sorts of things that I've done:
Style links to external sites differently than links to pages within this website. This gives you a simple, and quick, hint that you're about to leave the website.
Style examples and extra information differently than the rest of the body text. This allows you to quickly find examples, etc., and to easily skip past them if you're not interested, straight onto the next topic (you don't have to read through all the text to find the next bit, you can just scroll for the end of the box surrounding it).
On that note—of skipping past things you don't want to read about—my pages that talk about multiple things use headings between each section. So, if you're not interested in a particular topic you can whiz down to the next heading instead of having to read through an entire topic just to find something different.
Style navigational menus differently, and locate them separately, than the main page body content. Also, they're styled to disappear when printing (you can't click on links on paper, and they waste the space available to print the useful content of the page).
Of course, you need a browser that supports CSS to see the effect, and a decent browser to do a good job of it (i.e. not Microsoft's Internet Explorer—even now, in 2006, it's still a very poor product, not supporting standard features, or wrongly implementing them). Less capable browsers won't get the full effect, but the pages should still be quite readable. The pages have been authored properly, the styling is extra information for those browsers that can make use of it.