http://tweetsum.com/
TweetSum digests all your new followers, rates them using what they call the DBI (”Douche Bag Index”), a number that supposedly weeds out Twitter users likely to be annoying, and then lets you easily follow them back or categorize them as tweeps you don’t want to follow. You can see a list of recent tweets for each new follower as well, which is helpful.

Twitoria scans through your Twitter account and finds anyone who has been inactive for the past week, two weeks, month, two months, six months, or year.

http://twitoria.com/

Nest.Unclutterer will automatically block Twitter users who are following more than a certain number of people or who have been inactive for a certain number of days. You can specify those thresholds and white list certain tweeps so that they are exempt from the cleaning. Nest.Unclutterer is actually less about who you’re following, and more about making sure people following you are actually friends you want to be associated with.

We’ve had some reports that Qwitter hasn’t been as reliable lately as it had been in the past. An alternative service that also notifies you when you lose a follower  is http://twitterless.com/. If you really want to keep on top of when your followers jump ship, it might be a good idea to sign up for both services to make sure you have all your bases covered.

"Whats Qwitter"
Once you’ve done your initial cleaning, Qwitter is a nice app that will update you via email whenever someone stops following you. It will even let you know what you tweeted that caused them to stop following you, which could be useful (if you lose five followers every time you tweet about your cat, for example, that might be a hint to stop talking so much about your cat if you want to retain followers).

Friend or Follow does essentially the same thing as Twitter Karma, helping you figure out who your friends, follows, and fans are on Twitter. The difference is in the presentation, and it might be a little easier to use for those with a large number of follows or followers.


http://friendorfollow.com/

One of the most important factors when deciding whether you want to follow a Twitter user is what sort of content they tweet about. If someone tweets mostly about topics you don’t care about, they might not be the best person for you to follow. Tweetcloud creates a tag cloud of a person’s tweets to give you a bird’s eye view of the type of things they tweet about.


http://tweetcloud.com/

Twinfluence is a scientific approach to measuring the influence of Twitter users. It’s another set of metrics you can use to help you figure out who you want to follow.



http://twinfluence.com/

This button is very simple and its very smart. One code can generate a 100% custom link depending on what page you put it on.

The Retweet button is for website and blog publishers that want to encourage their audience to retweet their content on twitter.

We have made our button really smart, with one simple piece of JavaScript we are clever enough to give you up to date tweet counts and shorten

your title and link for the retweets. Best of all it will work on any web page, anywhere!

To get the codes go "Here"

This is a great little tool to manage your DM's, it has a good Followers Manager, a Profile Rotator, and you can send "Smart Tweets" which is basically scheduled repeated tweets.
The only draw back is you can only link one account and some features are disabled for the free account. But you could upgrade to the pro account and link up to 5 twitter accounts and have all the features enabled but it costs $15/mo.