[DaphneDiane]

Aye, the biggest downside with growl is it's customization depends a lot on the design of the applications using it. It has no true filtering of it's own from what I've seen, it depends on the applications breaking down messages into their own categories and their decisions on what to send messages for.

From one end: An IM client that sends a growl notifications all in the same category and sent one everytime someone typed a key at the far end would be scary in growl. On the other end an IM client that let you set settings for notifications for each member of your friends list, or even only set one message for the first message received while it was in the background would be much more livable.