How to find my lost Ubuntu laptop?

I am running Ubuntu on my laptop.

In case if I lose my laptop or it gets stolen, is there any way to locate it?
Do I have to install any application beforehand to find my laptop?

Yes, you will be able to find your lost Ubuntu laptop if prey was installed on it beforehand.

Install prey with one of the methods below:

• Via the Software Center, click the below button:

  

• Run the below commands in a terminal to install prey,

  sudo apt-get install prey
  

• Install from a .deb file.

After installing prey, make an account and you're done.

The free account allows you to use prey on 3 machines. If you need more functions or more machines you need to pay for the pro version of prey.

Prey can only be uninstalled if the thief knows the administrator or super user password. To prevent him from doing so they encourage you to add a BIOS password and disable booting from removable devices on your PC, so that the thief will be forced to boot into the previous installation and thus, not be able to format your hard disk easily.

Reference

For any further questions about prey, see: FAQ – Prey.

UPDATE: Prey version(0.5.3) available in the Ubuntu repository is not working properly, so download .deb file of prey(version 0.6.2) from the link I mentioned above.