TiddlyWiki lets you write ordinary HTML by enclosing it in {{{<html>}}} and {{{</html>}}}:
<html>
<a href="javascript:;" onclick="onClickTiddlerLink(event);" tiddlyLink="TiddlyWiki" style="background-color: yellow;">Link to wikiwords from HTML</a>
</html>
The source for the above is:
{{{
<html>
<div style="background-color: yellow;">
<a href="javascript:;" onclick="onClickTiddlerLink(event);" tiddlyLink="Macros">Link to wikiwords from HTML</a>
</div>
</html>
}}}
HTML can enable some exotic new features (like [[embedding GMail and Outlook|http://groups.google.com/group/TiddlyWiki/browse_thread/thread/d363303aff5868d0/056269d8409d121f?lnk=st&q=embedding+gmail&rnum=1#056269d8409d121f]] in a TiddlyWiki). However it doesn't work for some JavaScript code libraries; see CustomMarkup for another way to include custom HTML in your TiddlyWiki.Tiddler 'InlineHTML' in Namespace 'TiddlyWiki.com'
InlineHTML
JeremyRuston - 2006-09-29 14:01:00 (created: 2005-09-27 00:55:00 )
TiddlyHome 2.0 Beta