You can enable or disable a lab whenever you like. Here's how:
In Gmail or Google Calendar, click the Gear icon and select Settings.
Go to the Labs tab.
For each lab you want to use, click Enable. If you want to stop using a lab, click Disable.
Click Save Changes at the top or bottom of the page.
Save a common message and then insert when needed right to the compose window.
Provides a preview pane to read mail right next to your list of conversations, similar to the view in Outlook, Thunderbird, or AppleMail.
Oops, hit "send" to soon? Stop the messages from being sent for a few seconds after hitting the send button.
Google Calendar Gadget
Adds a box in the left column which shows your Google Calendar. See upcoming events, locations, and details.