Once you've set up your notification methods (SMS, Voice, IM, Twitter, etc) at AwayFind.com, you can use this add-on to set up AwayFind alerts directly from within Google Mail or Google Apps.
A small orange box with an arrow will appear to the right of the sender and the subject of emails you receive in Google Mail. Clicking on that box you can select a notification to dispatch when messages from that sender or on that topic are received in the future. You can also set this notification alert to expire in a day, a week, or never.
Each notification will contain a significant portion of the email you've received. You can tweak the settings for notifications you've set up (called AwayFind filters) by logging into awayfind.com.
If you want to see a 60-second video demo, you can check that out here.
-- As of now this is not a standalone add-on. You will need to setup AwayFind BEFORE installing this.