[Javascript] stationary buttons

[Russell Scheinberg]

I am looking for some help in finding how to create a button (most
probably in a layer, I guess) that will remain stationary in position on
a page as the page scrolls down, so that it never moves out of sight
along with the other elements on the page. I have seen this effect
somewhere recently with ads, but have not been able to find it since. Is
there a combination of DHTML, Javascript, and CSS2 that will get what I
want? I am afraid that this can only be accomplished with flash, but
that doesn't seem right. I need this to be a button that can submit a
form on the page. I have searched extensively for a tutorial or a page
where I can see this again and possibly look at the code, but with no
luck. 

Any help with locating an example, provding some pointers, or, better
yet, a tutorial would be really appreciated. By the way, I have
Dreamwever Studio MX, but have not been able to find a reference to this
in the documentation there. If you know how to do this in Dreamweaver,
that would help too. Thanks.