This information is primarily based on the software information in the math page of World Wide Web Consortium.
Some general information on different possibilities to present math in the Web.

SOFTWARE:

TechExplorer -plug-in 

Introductory-version is currently supporting a large subset of  commands in TeX, LaTeX and AMS-LaTeX (this means it doesn't support ALL of them).
In addition it understands a little of Mathematical markup language MathML.
You can insert hyperlinks, pictures, links to audio and video files, so called alternative links (links when clicked show an alternative text) to your text. And you can launch applications form your PC, have pop-up windows and menus with Techexplorer.

With the Professional -version you can print and control Texhexplorer with  Javan or Javascript.
Techexplorer Hypermedia Browser  is a trade mark of  IBM Corporation.

Enviroments: Windows 95 OR Windows NT with service pack 3, at least Netscape 4 or Internet Explorer 4.
NOTE! The UNIX version is coming soon.
Price: Professional Edition $28.

Home Page  of TechExplorer. Here you can also download the introductory version.
User Guide as a zip file
To view any examples you need the plugin installed into your browser. There are examples in the User's guide, and you can test your own Tex-files.
Examples: Koe.tex  Ana1198.tex  Checkout.tex
 

Pluses: + It suffices to know Latex or Plain TeX, the user doesn't need to learn any new languages + One can put Tex-files to the web as such, no intermediate steps or software needed + has interactive elements  + supports navigation in and between documents

Minuses: - the viewer of the pages has to install the plugin to his/her own PC - the plugin doesn't and won't work in Windows 3.1 - You can't print from the Introductory version

Hypertex

Enviroments: You can find dvi-viewers to both Unix and Mac. In Windows you can use a Java-applet called IDVI.
Price: - ,
An example that uses IDVI  as a viewer
More information on Hypertex
HyperTex FAQ

LaTeX2HTML

Enviroments: Unix. Price:  -
 LaTeX2HTML home page
An Example from the Latex2html home page

More examples Koe, Ana1198, Checkout.

Tth 

Enviroments: Unix, Linux, Windows, OS/2.
Price: free for non-commercial purposes
There is a commercial version Tex2HTML, the price depends on the number of users and where you use it. For example in academid server use with Windows the licence costs $150 for the first year.

A little example: Möbius mapping is

Textogif

 Htex

MathML related software

MathML means actually two different kind of languages. The first, so called Presentation Markup Language aims to convey the visual appearance of mathematical text. The second , Content Markup Language tries to convey the content of mathematical text. Then also other (mathematical) applications can understand what is it all about.

Amaya

WebEq

Enviroments: all enviroments that have Java Runtime Enviroment 1.1.5, and sufficiently fast processor. It probably demands at least Pentium 166Mhz, as working with Pentium 120 Mhz was hopelessly slow.
Price: A server licence with one editor licence $79, a server licence with 25 editor licences $195. A free 30 days evaluation version.

Home page
Example(Java-applet; it takes some time to load it)

Mathtype

Ezmath

{function f of x} = a sub 0 / 2 + sum from n=1 to infinity of (a sub n cos {n pi x}/L  + b sub n sin {n pi x}/L)

Maple and internet 

Conveying Maple files as text

# Let us introduce an algebra of linear recurrence operators in n and k.
     #  Sn and Sk denote the shift operators in n and k respectively.
     > A:=shift_algebra([Sn,n],[Sk,k]):
     # We compute first-order recurrences satisfied by the summand (which we
     # denote by h).
     > h:=binomial(n,k)*binomial(2*k,k)*(-2)^(n-k);

                                                         (n - k)
                h := binomial(n, k) binomial(2 k, k) (-2)

     > Sn-normal(applyopr(Sn,h,A)/h,expanded);

                                      -2 n - 2
                                 Sn - ---------
                                      n + 1 - k