I would love for some simple HTML(5?) API where certain anchor elements automatically show up on the scroll bar. That way, for instance, you could have a huge document split into chapters visible from the scroll bar, or a blog post where you can just glance at the scroll bar to see how long the article is and how many comments there are.
You mean like iOS style? That is a pretty good idea. I've certainly seen it done with custom boxes but it would make a nice addition to the browser chrome in the same way that the link element can be.
Something like `<a rel="scroll">`