A reusable, JavaScript class to animate a bubble formed underwater floating up to the surface. I also have a real-example work-in-progress of it at http://ed.aetkinzstudios.com.
I'm quite happy with the result myself, going forward that's definitely the way to make animated user-interface elements. I think I may create a tooltip like that especially since making a jQuery tooltip plugin means that I'd be pretty much tying the tooltip to a specific method of triggering. Like on a certain element's hover or something, and sure I could open it up by using callbacks and settings I think that will always change project to project. So what I want to do is create a reusable tooltip object with a constructor so I can write var tooltop = new Tooltip("message", x, y); inside of any jQuery or other framework event handler that I want.