I have been on a few GTA forum type sites and a few have a very useful feature, when you get a PM or a notification, you would get a number pop up on the top of the tab (the number of messages or notifications), I am usually browsing the internet with multiple tabs open and I and many others would find this much more efficient than constantly checking our notifications and messages. It's a plugin for IPB (I think), called Instant Notifications Hook.
Example of how it would look: 
