Games like World of Warcraft have been using mobile authenticators to prevent account theft. Google also has a similar application for mobile phone users. The app can be downloaded from Android Market or iTunes store.
Once you install the application on your phone, its time to setup the Gmail account to use a 2 step verification process for login. Now when you need to login to your account you need to enter the username and password. Then your will reach a page which asks for the verification code as shown below. Since you need the mobile app to get the code, it makes it extremely hard for people to hijack your gmail account.
Enabling the 2 step verification increases your Gmail accounts security a lot. To make it even more secure, go to gmail settings and under the browser connection, enable the always use https option.
Read our other posts about Gmail to increase security and functionality of your Google account.