Examples of well-displayed mathematics on the internet I'm interested in hearing of examples of mathematical (or, at a pinch, scientific) websites with serious content where the design of the website actually makes it easy to read and absorb the material.  To be absolutely clear, the mathematical content of the website should be on the website itself and not in an electronic article (so meta-sites that make it easy to find material, like MathSciNet or the arXiv, don't count).
Edit: I'm extending this to non-internet material.  I want examples where the design of the document/website/whatever actually helped when reading the material.
As a little background, I know that LaTeX is meant to help us separate content from context and concentrate on each one in turn, but I often feel when reading an article that the author has concentrated solely on the content and left all of the context to TeX.  This is most obvious with websites where there are some really well-designed websites to compare with, but holds as well with articles.
 A: I'm not sure the previous answers really address Andrew's question, which is about design and readability, not asking which sites have useful content.
Among math blogs, I find Terry Tao's to be the most well-organized and easy to look at.
A: The Tricki has an innovative design.  The basic format is similar to Wikipedia's, in that it's a wiki that displays math as images.
However, it uses a "hiding" idea in order to provide detail at various junctures during a text.  This is intended to solve a common problem in mathematics texts: what level of detail should one provide?  If you provide too little, your text is unreadable; if you provide too much, it clutters the main point.
The Tricki solves this problem by having sections of the text hidden, but which can be expanded to provide more detail.  Thus, you can read the text and get the point, while still being able to confirm any details along the way.  This seems like a very elegant solution to me.
The overall organization of every article is nice, too: it begins with a quick description and prerequisites.  It continues with general discussion littered with many examples and formatting that emphasizes the main points.
A: Hi, 
For french speaking readers, there's an example of discussion forum 
using latex2html to generate a nice display of mathematical forumlas:
http://www.les-mathematiques.net/phorum/addon.php?0,module=recent_messages 
It is realized using the Phorum php framework ( www.phorum.org ), 
and is easily customizable (the addition of a latex2html module 
 is part of this customization).
But I don't know if something similar exists for english speaking users.
Best regards,
Eric 
A: The best two sites I can think of for that one are Wolfram MathWorld and Wikipedia. Mathworld has a lot of good information on just about everything in mathematics. For as much as some people hate Wikipedia I find it has some of the best information in math and "hard" sciences.
A: I stumbled across The EPINET project site once.  It doesn't appear to be updated anymore, but it does have a lot of information on hyperbolic tilings and networks.
