Popsters - Analyze your social media pages and spy on your competitors
Narrow - Narrow helps you build a targeted audience and increase your influence on twitter.
Content Marketing Stack - A curated directory of content marketing resources
Follow3rs - Follow3rs enables you to add more followers to your Twitter account and become prominent in no time at all.
SocialRank - Graph search for TWTR. Filter by interests, location, etc
Followerion - Followerion is the most trusted site regarding how to get more followers on twitter.