Twitter, the real-time short messaging service that works over multiple networks and devices, continues to grow exponentially, increasing its membership from 500,000 in Dec. 2007 to 4.43 million in Dec. 2008. Membership is not the only area Twitter has grown. So has the number of tools, including Tweetfeed.

What is Tweetfeed and why does it add value to Twitter?

Tweetfeed is one of the newer applications that allows people to create customized search term feeds, and track those topics in real time. What makes it stand out from Twitter's native topic search engine, in addition to presentation options, are the search operators.

Feeds can be generated based on exact phrases, either or phrases, from specific dates, by attitude, sent to or from specific people, and within a certain proximity, among others. There are sixteen operators, assuming you count some basics such as hashtags (#) or attitudes (which is basically a smile or frown search).

We used it a few days ago to help capture a conversation between Shel Israel and Scott Monty. It proved more useful than toggling back and forth between the two in order to find the start of their conversation on Twitter's native search engine. It also made it easier to capture portions of the conversation that occurred hours apart.

Tweetfeed is also "Share This" enabled, allows for custom CSS presentation, and Web analytics. (The combination of features, along with larger type, makes it ideal for "Twitter walls" that are becoming more common at conferences.) The customization features add flexibility.

You can find a list of five potential applications here as well as links to three comprehensive lists of Twitter tools.