Gmail Labs is a testing ground for experimental features that aren’t quite ready for primetime. They may change,break or disappear at any time. If (when) a Labs feature breaks, and you’re having trouble loading your inbox, there’s an escape hatch. Use http://mail.google.com/mail/?labs=0.
Custom Date Formats
Adds options to the general settings page allowing the date and time format to be changed independent of language. For example, you can use a 24-hour clock (14:57) or show dates with the day first (31/12/07).
Allows you to insert images into a message body. You can upload and insert image files in your computer, or insert images by URLs. This lab will not work if you have offline enabled.
Mark As Read Button
Tired of spending all that effort to click on the more actions menu every time you want to mark messages as read without reading them? Now just enable this lab and that is just a button click away!
Pictures In Chat
See your friends’ profile pictures when you chat with them.
Quote Selected Text
Quote the text you have selected when you reply to a message. (Now works with the mouse, too!)
Send & Archive
Adds a button to the compose form that lets you send a reply message and archive the email conversation in a single action.
Sender Time Zone
Should I reply to this mail or just call the guy? Ooops… it’s 1 am. Sorry, I didn’t mean to disturb…
Places your signature before the quoted text in a reply, and removes the "–" line that appears before signatures.
Adds additional star icons. After enabling this feature:
(1) Go to the "General" Settings page to choose which superstars you wish to use.
(2) Use either the keyboard shortcut (‘s’) or click to rotate through your selected superstars.
(3) Use the search operator "has:" to find all messages with your superstar (e.g. "has:red-bang", "has:blue-star"). Learn the name of a superstar by hovering over its image in the "General" Settings page.
Oops, hit "Send" too soon? Stop messages from being sent for a few seconds after hitting the send button.