Tweetastic - Better Twitter analytics, scheduling and more
ilo - Premium Twitter analytics
Followerwonk - Followerwonk by Moz is a Twitter analytics tool to help companies better understand their Twitter followers.
Accountanalysis - A tool to evaluate Twitter accounts
Twitter Ads - Twitter offers targeted ad placement on their ad platform.
Secateur - Use Secateur if you want to temporarily or permanently block or mute (or both block and mute) a Twitter account and all its followers.