When hovering over things like [notes], [bios], [review], etc. in the Tag Window, you get this great tooltip that allows you to read the tag contents without actually opening the tag up.
I asked for "keep the tooltip open while the mouse is over it" a few years ago, and still think it's a good idea... for the tag window.
I don't think this would be too great for tooltips in the file list, as they are already a bit "in yer face" there.
-marko