If you needed to group your friends by category for easy retrieval prior to Twitter's latest list feature, you had to create your own system or use third-party applications and listings like Wiki's and Media On Twitter, Twitter Packs, Social Brand Index, and List of Twittering Journalists. It can become cumbersome if you work with multiple windows and tabs open at once.
For the PR community, this new feature is a wonderful tool. Now PR pros can list media by beats for easy monitoring and communication. I've spent countless hours organizing my lists and also snooping through other Twitter user's lists since the addition of this new feature. You can make your list public or private.
As a media-monitoring tool, it's useful for learning who is tracking your clients because their page will list all of the public lists they belong to. It's also entertaining to see how some users categorize the people they follow on Twitter. Some amusing classifications were funny people, perverts, comic-relief, and trending-topic-makers.
In summation, here are my top reasons why this is a valuable tool:
You can organize your twitter friends by importance, frequency of communication, and/or classification based on your relationship to them.
You can learn the importance of your contribution to the Twitter world based on the number of public lists you are on, as well as how many people subscribe to a list you have created.
You can learn a lot about the influence of your clients by evaluating the number of lists they are on and what type of classification they are listed by.You can ascertain how your followers use Twitter by looking at their lists as well as evaluate their importance to the social-media community based on the number of lists they are on and by their classifications.
You can find valuable new followers based on viewing the lists of your followers and those who follow you.
To learn more about Twitter's new feature, use the following resources:
If you needed to group your friends by category for easy retrieval prior to Twitter's latest list feature, you had to create your own system or use third-party applications and listings like Wiki's and 
