TwitArea is a a Firefox add-on for Twitter that allows users to easily insert and share location information when tweeting. The company describe it as "TwitPic for places".
TwitArea adds an 'Insert Place' button to Twitter. Clicking on the button lets you add a short URL for your chosen location.
The short URL links to a place page, that contains contact info, location on a Google Map, and space for others to vote and comment.