Multiple Inboxes: You can see different sections like starred messages, drafts, unread mails, etc in the Inbox window itself. You can choose which category you want to view. If you want to display starred messages, go to Settings | Multiple Inboxes and in the search query plane type is:starred.
Undo Send: You can recall the email which you have sent by mistake/accident. This feature can stop the messages being sent. It lets the users to abort or stop the delivery of any Gmail message within seconds of sending it. To activate go to Gmail account | Settings | Labs and you will find a feature called Undo Send . Now just click on the “Enable” radio button.
Docs and Calendar Gadgets: You can easily access Google services like Docs and Calendar in Gmail itself by enabling the Google Docs and Calendar gadgets. They are placed in the left column. You can easily view starred docs, add reminders and so on.
Inserting Images: Usually when we want to send images, we’ll send it as an attachment, right ? These attachments are not seen on the email body. Those are old times. You can directly insert the image in the body of the message. To activate, go to your Gmail account, then Settings | Labs | Enable Inserting Images Feature.
Tasks: By enabling this feature you can easily list down reminders and tasks without opening another application. To use this feature, click inside the task window and enter your to-do list. You can also create directly from emails also, select the email you want to add and from the More Actions dropdown button, click on Add to tasks to add it to the list.
Quick Links : You can quickly access frequently search pages or important messages by this tool. It helps you to add links to any page that you have opened up in Gmail. You just need to click on Add Quick link and type in a name for the page being current viewed. By clicking that link you can directly go to that page.
Mouse Gestures : You can quickly navigate Gmail Pages with your mouse using this feature. Right-click and moving to the right will take you to previous pages, moving upwards takes you to the main inbox if you have opened a particular message.
Canned Response: You can use this feature for sending the same content to all of your friends. You need to create a template. To do this, click on the Canned responses link in the compose mail window and select New canned Responses, type in a name and select the template you have created. To insert a response, click on the Canned Responses and select the particular template you want to insert from the Insert section.
Offline: You can now access Gmail even when you are offline. You can do tasks like sending, reading, labeling, searching and so on. It will synchronize your mails from Gmail server to your computer when you are connected to the net. You need to have Google Gears installed if you are using IE or Firefox. Chrome users no need to install.
Search Autocomplete: If you are searching Gmail frequently then this feature will be useful for you. It helps you in searching Gmail faster by providing suggestions as you type. It displays contacts name and also similar phrases.