Just follow this url and play with "Click here to notify" button.
http://jsfiddle.net/dandv/wT26x/1/
Advantages over current flash notifications: browser shows it over all windows so you can receive notifications while browsing web or working with other programs.
You can use it for current notifications like "you've been kicked", "leader closed lobby" etc.
Or you can put a button like "Enable rich notifications".