Recently I'm impressed more and more with Google's Chrome browser. All kinds of small touches present themselves from time to time. I've noticed the tab closing behaviour recently pointed out by theinvisibl. What I want to point out though, is the behaviour of Chrome when you click on a HTTPS link and the server responds with in HTTP. Here is an example:
Take care to notice how HTTPS in stricken through and coloured in red. Just another small but visible touch adding to the visual appeal of the browser. Further it adds a bit to the security awareness of the users.