Pretty sweet application free from the mac app store that tells you how much memory you're using. This application really gives you a feel for how much memory everything uses. You'd be surprised when you're 2GB mac goes from 40MB free to 1GB free. Don't be alarmed if you force quit everything and noticed you still only have 1GB being used. I'm not sure on this you should ask an expert but I believe Airport, Graphics Card, Sound Card, etc use your RAM. You might not want this 'free' application, it might cost you. Wait..what? You might go looking for more ram lol! I actually ended up ordering 2 x 4gb sticks from crucial.