I just tried many of these (I did not know they exist) and these applications are GREAT!
This site is AWESOME because you can look up keywords, then mass follow people who have either tweeted about that keyword or have it in their profile (it lets you choose either option). It also lets you know how many followers they have and you can see information and stats about them. It is really easy and quick without any additional signing up for things. All you need to enter is your Twitter username and password.
This site is for you to see different stats about your Twitter account. Also, no additional sign ups... just your username and password. I just signed up and it already has stats for me. So easy to use!
This site scores and analyzes you based on your tweets, retweets, following, etc. I am still figuring out what everything means, but is very easy to use. All you have to enter is your Twitter name and it will automatically score you. Pretty interesting stuff....
This site is fun to look at and has MANY different things you can do! This site is also the best to mass follow or unfollow (if others are not following you back). I suggest you take some time to visit and poke around here! No other sign ups required. Soon, you will also be able to see recent unfollowers.
I hope you find these links useful and easy to use! Do you have other links or experiences to share? Please comment below. I will possibly edit and also link your shop to the post! Happy Tweeting!