If you happened upon nj.com in the last month, you might have noticed a clucking penguin waddling across the computer screen, stumbling over text as it promoted a local utility company. On a cricket league chat board in New Zealand, exasperated users have been deluged with floating squares that try to interest them in mattresses, dating services and officially licensed trinkets from the "Lord of the Rings" film trilogy. On the Web, the floater's time has come. Not to be confused with pop-up ads, which open new windows and clutter virtual desktops, these floaters, or overlays, or popovers (no one...