These Twitter tools do genuinely useful stuff but less people know about them. That's fun. Oh -- and some of these tools are just that: fun.
Followfriday Helper
Don't miss recommending your best buddies on Twitter; the people that actually interact with you and/or retweet your material.
Filter based on retweets sent or received, on recommendations received, on favorites, or on @ replies.
IDFromUser
Used to be finding your user ID was easy on Twitter by a quick look in the source code. Not so much anymore. That's why we have this tool.
By the way, Jack Dorsey has the lowest Twitter ID: 12. The highest is the person who just signed up.
Exquisite Tweets
Rebuild a Twitter conversation on one page. Save it or screenshot it and you can easily reference a Twitter thread on your blog. Or make sense of an ongoing debate 
Fake Tweet Builder
Just plain old fun. Type in a conversation and the tool turns it into a "real" Twitter convo. You can set handles, names, avatars, backgrounds -- even the Twitter client!
Fun
TwitWipe
Why you would want to do this? As the home page says;
TwitWipe is a tool to wipe or delete all your tweets in one go. You may need to do this to start over, to clean it out before handing the account over to someone else, or maybe you've just realised how shitty your tweets are.
Can't argue with that.
Beats deleting your account; with TwitWipe everything stays as is (account, login, permissions, ID, followers, following) except you get rid of all your tweets.