I'll admit it's been awhile since I'd thought about this product, but, a question on the autocad discussion groups reminded me of it today when I recommended it to a user.
They were looking for a way to display the name of a block when they hover over it.
I had to think for a second to remember the name, but, it finally came to me, Bubble for AutoCAD!
I used this plug-in a lot when doing drawing cleanup from outside companies. Sometimes I couldn't quite tell what their blocks represented, or things weren't bylayer... having this pop up and tell me the layer usually gave me the clue I needed.