I've been using Growl for some time now, and I will never run without it.

It adds functionality to other apps that are invaluable and make many of the things I do easier. The many options of display are great, I can choose whatever I one I want.

It lacks some docs, but it is so basic that it isn't really needed.

I only have two features to request.
Firstly a beep along with an alert or instead of an alert.
And Secondly, a way to make custom alert boxes.

Thanks for the great app!