If your a fan of Google's Gmail, then you'll want to check out Gmail Labs.

Often missed, the Gmail Labs link can be found on the top right hand corner of your Gmail inbox. Gmail Labs is the testing ground for Gmail features that aren't quite ready for final release, but still made available for Gmail users to try out. The downside is that features may at anytime be change, break or be removed.

Here are a few of my favorite Gmail Labs Features that will enhance and optimize your user experience:

1) YouTube previews in mail
Shows a video preview whenever you receive a YouTube link in an email. You can watch the video right inline!

2) Yelp previews in mail
Shows previews of Yelp listings (rating, location, phone number, etc.) whenever you receive a Yelp link in an email. This is a must have for the Yelp Fan.

3) Message translation
Uses Google Translate to translate messages you receive in other languages.

4) Canned Responses
Email for the truly lazy. Save and then send your common messages using a button next to the compose form. Also automatically send emails using filters.

5) Forgotten Attachment Detector
I know we all make this mistake from time to time. This feature prevents you from accidentally sending messages without the relevant attachments. Prompts you if you mention attaching a file, but forgot to do so.

6) Vacation Time!
Dont forget to turn on or off the vacation responder. This feature lets you specify starting and ending dates for the vacation autoresponder.

7) Create a Document
Allows you to create a Google Document from an email conversation or a new blank document if your keyboard shortcuts are enabled by hitting 'g' then 'w'.

8) Text Messaging (SMS) in Chat
Allows you to send and receive text messages (SMS) in Chat. US phones only for now.

9) Authentication icon for verified senders
Displays a key icon next to authenticated messages from certain senders that spammers attempt to fake. Currently works for mail from PayPal and eBay only. We all could use the extra line of defense against those sneaky spammers.

10) Undo Send
Oops, hit "Send" too soon? Stop messages from being sent for a few seconds after hitting the send button. I know there are a handful of you wishing you could have had access to this feature sooner.

11) Got the wrong Bob?
Doh, have you ever addressed an email too quickly, and included Bob (your boss) instead of Bob (your friend) by accident? If you're emailing more than two people at once, Gmail will check if you meant to include Bob Smith rather than Bob Jones based on the groups of people you email most often.

12) Inserting images
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.

13) Google Calendar gadget
Adds a box in the left column which shows your Google Calendar. See upcoming events, locations, and details.

[Google Labs]