Is it possible that I can change my screen timeout to never? I am using Nexus S. Currently, the maximum value I can set for screen timeout through settings is 30 minutes.
I think you are searching for this app Keep Screen Lite. It allows you to keep your mobile always awake for some of the applications. You can set the applications to not to screen timeout.
You can set it to stay on as long as it's plugged in. To do that go to Menu -> Settings -> Applications -> Development and choose Stay Awake.
Let me just warn you, the Nexus S has a Super AMOLED screen and you can burn in the images on the screen. I have burn-in of the Time and the notification bar on my screen. it is only noticeable when i have light colored wallpaper, but it is there.
Samsung even removed the "Stay Awake" option from the Galaxy S Vibrant line (possibly others as well) in their TouchWiz UI. The Nexus S will still have it, because it is a Vanilla Android.
The screen is also one of the biggest consumers of power, so if you leave your screen on all the time, when not charging, expect to see poor battery life.