Enhanced datatips are my favorite new debugger feature. However, sometimes you want to see underneath the tip without losing your spot. Fortunately, JimGries thought of that. You can make the DataTip transparent by pressing the ctrl key or middle mouse button.

Here is an Enhanced DataTip In Visual Studio 2005:

EnahncedToolTip

Here is the same DataTip with the Crtl key pressed:

 EnhancedToolTipWithCtrlPressed

Update: JimGries pointed out that you can also make the DataTip transparent by pressing the middle mouse button (or wheel).  If you have the wheel (and who doesn't today) you can also scroll with it, just as you'd expect.