Twitter productivity tool - allows scheduling of messages, and a variety of other tools to help you "be" in Twitter without actually being there! Apply caution - People like true engagement! (Well durrr)
Clean up your Twitter account, by finding those who rarely tweet, who have no profile picture, who don't engage or respond, who over-promote themselves - allows for better relationships and likelihood of engaging new business/relationships
Kred - Measures influence based on the propensity of others to share your content and mention you, as well as your outgoing engagement (Mentions and RT's for Twitter, for example)
Inboxq find questions being asked in social media (Twitter) by recognising questions around the keywords you provide. You can also refer a question to your trusted contacts, for them to answer, and create new, targeted connections as a result
URL shortener, for use in Twitter and other social posts and updates, which allows click tracking - how many people clicked your links? Bit.ly shows you what posts have caused the best reaction and engagement.
Measure influence - in this context, a user's ability to move content across the social web. Measures FB, Twitter, Linkedin and Google+ (with ither networks providing limited influence on scores)
Buffer takes your tweets, and sends them at the optimal time - the time at which your followers have shown themselves most likely to see, share and clickthrough on links.
One of the greatest tools you will ever find ... If this then that makes it easy to cause various actions to happen, based on your interactions via social media - check out the recipes for some ideas!