Today, Gmail introduced Gmail Labs, a portal for all new experimental Gmail features. Gmail labs gives users access to all new and upcoming Gmail features which are currently under development.

The new experimental Gmail features are created by Google Engineers in their 20% time and are not guaranteed to be 100% stable.

Gmail Labs can be accessed from Settings → Labs from within Gmail and you can choose from a total of 13 unique experimental Gmail features. My favorite ones are Pictures in Chat (Avatars in Google Chat) and Mouse Gestures (Navigate around Gmail using quick mouse gestures).

As these features are experimental so there is a good chance for a Labs feature to break at any time. For safety, bookmark the following link which is an escape hatch to access Gmail normally by disabling all Labs features in case something goes wrong.

http://mail.google.com/mail/?labs=0