As a result of a search for flight options, United Airlines presents users with a long scrolling list of departing and returning flights. The associated "Continue" button, however, persistently displays by "floating" in a constant location--about 40 pixels from the top of the browser viewport:
United could have framed the scrolling display of flights, which would have also provided a persistent Continue button (a technique used in many applications). I'm not sure of the advantage of the floating button, other than it definitely catches your eye as it jumps into position.
Alaska Airlines also has a floating page element - but it provides a persistent display of the flights you've selected as your scroll up and down through the options:
Interestingly, you can pin this element in a static location on the page - presumedly for users who might find the jumping behavior annoying.
