I want to create a service that allows diverse web site owners to integrate material from my web servers into content served from their own servers. Ideally the resulting web page would only be delivered from the web site owners server, and the included content would be viewed as being part of the site by Google - which I think would rule out iframes or client-side Javascript to get the content from my server (although I may be wrong about that?).

Also the data wouldn't actually be updated that often, say once a day, so it would be inefficient to get the data from my web servers with every request. Finally, the method needs to be as simple as possible so that it is easy for web site owners to integrate into their own sites. Are there any good methods for doing this sort of thing?

If not then I guess the simple way is with iframes or Javascript.