FriendOrFollow is a twitter serveice that helps you find out Who are you following that’s not following you back? Who’s following you that you’re not following back?

Your Twitter Ratio is the ratio of your followers to friends (or people who you follow). It is measured with the TFF Ratio (Twitter Follower-Friend Ratio). The higher the ratio, the more Twitter heat you pack.

Twitterless tells you who stops following you and graphs your follower history over time, making this info available in a variety of useful views.

TweepMe is the 100% opt-in group of Twitter users who all chose to follow each other on Twitter. When a new member joins, every other member automatically follows the new member, and the new member follows them back.

You get information on your Twitter profile as to how many people follow you and you get notified when someone follows you. However, there is no notification when someone stops following you and you generally don’t have any insight into when people follow or leave you.

Clutter is pervasive. Twitoria tries to reduce Twitter’s clutter by revealing friends you are following that haven’t posted an update in a while. It can, for example, easily track down those pesky friend spammers that post no content, or people that have abandoned Twitter for another status updating service. Why follow them if they no longer tweet?

TweetSum does one thing and does it well: we show you at a glance who’s following you, give you the tools you need to decide whether you should follow them back or not, and let you quickly add or dismiss your new followers.

Tweepler Is an easy, more enjoyable way of processing your New Twitter Followers. View a list of New Followers and classify them in one of two “Buckets” Follow and Ignore.

Tired of shallow e-mails from Twitter when someone follows you? Want to know more about the people who are following you? Twimailer is a free service that delivers that information right to your inbox!

twitTangle is a free service that helps you untangle the mess of having too many friends on twitter. We allow you to rate and tag your friends and then filter your timeline to help you easily find the tweets that are most important to you! NEW Now you can create custom groups of your followers and filter your timeline by that group.

A twibe is a group of Twitter users interested in a common topic who would like to be able to communicate with each other. On each twibe’s page, there is a list of twibe members. There is also a tweet stream that lists tweets from twibe members which contain key word tags.

SemanticTweet is a simple web service that generates a FOAF RDF document for you from your list of Twitter friends and followers (or more specifically, from the 100 most recent of each of your friends and followers). It does this using the Twitter REST API. This service uses public Twitter data only, and so doesn’t need your Twitter username or password.