Tooltips kick freaking ass.
I mean, of course, that little help text that appears when you mouse over things. Tooltips are awesome because they are super ignorable and yet super helpful. It makes software self-explanatory in those areas where a little more explanation is necessary. The other cool thing about them is that when you know what you are doing and are moving fast, you don’t see them at all! Completely invisible. When you are going slow the computer supplies you with a little more info in the exact place your eye is looking.
I predict that we’ll see a rise in the ways, places and uses people think up for tooltip-like technologies. I suspect we’ll see tooltips in places we can’t imagine.