Laptop + 1 external screen = great. Laptop + 2 screens even better.
Adding a second screen to your laptop or workstation provides a great way to increase productivity. It allows you to spread out your windows and take advantage of all of the real estate. If you are using a laptop and you want to add a 3rd screen I found a nice external usb adapter from Arkview which runs about $80 and allows you to plug in a DVI monitor or VGA using one of the adapters. The screen resolution works great but the screen does refresh slower so its not idea for production but if you need a extra screen for email, browsing or other non-motion window it works great.