Endless scrolling, dynamic effects, and sticky elements are a growing trend on the web today.
Sticky Sidebar is one such example of a well done jQuery plugin that provides a sidebar that followers the user as s/he scrolls down the page without being overly intrusive.
This jQuery plugin allows you to set a number of sidebar or floating boxes that follow the user down the page as they scroll. The plugin uses absolute positioning calculated from the original css and offset to either the closest positioned parent or to the document. The plugin has been tested in IE6-9 and all the other major browsers.