Narrow - Narrow helps you build a targeted audience and increase your influence on twitter.
Listr - Listr lets you explore some of the best lists on Twitter, curated across your favorite categories.
MyFollowers - myfollowers.us is the answer to how to get more free followers on twitter. Start using www.
Refined Twitter - A browser extension that improves the Twitter experience
Follow3rs - Follow3rs enables you to add more followers to your Twitter account and become prominent in no time at all.
Vicariously.io - Create Twitter lists based on the follows of other users