OmniHTML is the part of OmniWeb’s architecture that actually renders parsed HTML and decoded images for display in a view. It also provides some conveniences like URL dragging and file downloading that come in handy if you’re writing something like a web browser.
You can download a sample application, OmniHTMLViewer, that uses this at http://www.omnigroup.com/ftp/pub/software/Source/MacOSX/Applications/
– AndrewDunning