The other day Anton asked for instructions on how to make a tabbed river like the one I have at tabs.mediahackers.org.
However, I am happy to provide the source for the site. It's just an outline. I think if you puzzle it out, you can see how you could modify it to display your rivers.
This outline is served by the worldoutline software. It's just very low-level stuff. But if you're motivated, and have hacked at HTML before, I bet you can do something with this. :-)
Feel free to use the green button to ask questions, comment.