Block Together - A useful tool which helps you block trolls on Twitter.
ilo - Premium Twitter analytics
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.
Tweetastic - Better Twitter analytics, scheduling and more
Moderate - Identify, mute, and block trolls in your Twitter feed
ClockTweets - Schedule, analyze, and stalk challengers on Twitter