Five methods are used for presenting Go diagrams in HTML:
Other methods may be in use: look for some Go pages, particularly those which present problems, and see how they do it.
Method 1 is described on the Chinese diagrams page.
Method 2 is used in http://www.britgo.org/intro/intro3.html.
Method 3 is described on the example page and used in the pages linked to by http://www.britgo.org/bgj/bgj.html.
Method 4 looks like this:
. . . . . . . . . . X . X . . . . . O X . . . . . . O , . X . . . . . O . . . . . . . . . . . . . . . . . . . .
A snag with method 4 is that it is necessary to make it clear that this is an upper left corner.
Method 5 is described on Mori's Go page.
It requires a java-enabled browser, and does not work perfectly with some browsers. It requires the browser to be connected, so that it can collect the java code from Mori's site.