Twitter

Yellow = I tested it. I found it useful, and I recommend it.

Add a "Tweet" button to all your Blogger posts in one shot:

http://www.bloggerplugins.org/2010/08/twitter-share-buttons-for-blogger-tweet.html

Echofon - Use multiple twitter accounts on iPhone

http://www.echofon.com

Twitter Resources

http://twitter.com/about/resources

Friend or Follow

http://www.friendorfollow.com

Follow Friday Helper

http://followfridayhelper.com

CrowdFireapp.com

iOS app allows you to unfollow those who have unfollowed you, allowing you to follow more people - Free

http://crowdfireapp.com

Klout

http://klout.com

Tweepi

http://tweepi.com

Twiangulate

Search for like-minded real people. Twiangulate does twitter bio search.

http://twiangulate.com

ManageFlitter

Allows you to unfollow 1000 people every 24 hours - Free

http://manageflitter.com

Tweet Big

http://tweetbig.com

Tweet Chat

http://tweetchat.com

Twitter Auto Followback

http://twitterautofollowback.com

Twitter Friends

Statistics about a given twitter profile - Free

http://stats.brandtweet.com/

Twitter Mobile

http://mobile.twitter.com

Hoot Suite

http://hootsuite.com

Free Autoresponder

http://www.vicconsult.com/twitter-autoresponder-auto-reply/

5 more tools

http://inspirationfeed.com/2011/07/5-twitter-tools-to-boost-your-productivity/