What Jeff said w/ regards to Power Auras.
It's a very powerful tool, but it requires a decent-enough sense of interaction design to make it work for you. The difference between totally-useless information overload and a clear alert system that almost scripts your interactions for you is entirely in the hands of the user.
I do something a little similar with
[Serendipity] stacks in that I make the interface clearly explain how many stacks and how long I have: At just one stack it's a small version of the spell icon with low opacity. With each stack the spell icon gets bigger, more opaque, and red.
The underlying trick is to "harness the built-in properties of the underlying architecture". By this I mean that humans process the meaning of images
way faster and better than text. Use this to your advantage.