Try it now. Use the scrollbar and scroll down the page and back up. Notice how the menu floats gently back into view as you scroll?
The affect has been enhanced here by using a special layout and nice graphics to give the affect that the menu is on a "rail". You can make your floating menu (or image or text or whatever you can put in a DIV element) as complex or as simple as you like.
1) Open up your webpage document in Notepad
4) Put your content in place of the "<b>Your Content Here</b>" content