Jquery scroll question

Hi guys,

Im attempting to find a plugin or someone who may know how i can achieve the following affect.

I want to have a vertical set of buttons on the side of my html container.

The buttons will be linked to anchor points on the page (in order to link to certain content.

When a button is clicked (or if you scroll down the page manually) and it scrolls to the content i would like the navigational buttons to scroll down with you rather than remain static, because a static navigation will be taken out of the container and will always remain in the same position on the page.

Any ideas how i can make this work...i have seen it done but dont know what to look for,.

Thanks