Here it is my new creation, Xbox growl style.
Some weeks ago I saw this picture in Engadget web page and since then I wanted to create a similar notification style for Growl.
After checking different combinations I finally came up with this Growl style. I have to say that I would like to find a closer font to the one used in the new Xbox dashboard notifications, but I haven't found it yet. Also, I had added a white border around it because whenever the image is dark and your background is dark, it can be difficult to see. Also, I kept the image height and width proportional so it would not be stretched.
Please download it here.