Thanks to @filiptepper I came across a Web service called Pusher.
If you're too lazy to click and read through the site - it's a service that simplifies creating realtime Web apps. Basically they act as a backend for your app and provide you with API needed to implement whatever realtime app you want. After a quick look I was interested enough to sign up for their beta plan. Gonna have some fun with it soon so stay tuned for a post about it. Meanwhile follow Filip on Twitter since the guy is a great dev and source of interesting resources :).