Resources for getting maths on to the web. One thing that came out of Terry Tao's recent blog posts on this matter (first post and follow up) is that it's hard to get an overview of all the different ways of getting one's amazing mathematics onto the web.  I thought it'd be useful to gather together a list of such.  This meant to be a list of ways to do it, not examples of where it's already being done.
Standard community wiki rules: one thing per answer and feel free to edit other's answers.
Additional rules: it'd be useful to have a little more than just links.  A brief description, pros and cons (be objective), platforms (does it only work on Linux, sort of thing) - things that might help someone decide which things to examine further.
 A: The standard way these days is of course writing LaTeX and compiling it to PDF.  The most obvious problem with this is that LaTeX is a typesetting system and is generating output which is supposed to look good on the page.  This doesn't necessarily look good on the screen, and I suspect most reading of things people download is done at the screen just to avoid drowning in paper.
A: You can also install MediaWiki, the software used for Wikipedia, with LaTeX support, on your own server (say, your own domain or a department server);
http://www.mediawiki.org/wiki/MediaWiki
Possibly useful for things like a study group for problem sessions or a textbook where multiple people work on the same problems, which not only helps to spread solutions but also to practice writing mathematics where others will see it. If you need to copy the code for some reason then you can just view the page wiki code.
This may also be useful for departments to keep track of their various seminars. Any attendee of the seminar could post their notes on a wiki. A collaborative, published effort may increase interest, especially amongst the undergraduates and graduate students.
A: There's a group at the University of Alberta that's been developing an XML/VMRL webpage for delivering mathematics in a hyperlinked, interactive environment. 
http://cougati.net/
The linear algebra and calculus sections are reasonably well developed, some of the other sections are in a transition phase.
A: For HTML pages and blogging services there is http://www.yourequations.com/ 
