I'm curious; how did you do that widget on the SO FAQ page, where the question sidebar scrolls up with the page until it reaches the window top, then stays put while the rest of the page continues to scroll?
This menu is warped with a div, starting with parameters
position:relative. This div is positioned on the right place using the rest struct of the page.
Now a script runs and when the top of this div is getting out of the screen this div get the style
position:fixed;bottom:0px. This now make it stay as you see, at the same fixed position.
You can call that floating menu, and I have found and use in the past relative to that style here : http://www.dynamicdrive.com/dynamicindex1/staticmenu.htm