Many are made from other people and companies that (in my opinion) Twitter endorses because they take the wide variety of ways and versatility to whole levels of using Twitter. It's definitely a ton of them out there.
Oh, is the page where we can ask to follow each other's tweet by following each other? I'm still somewhat sort of a newbie on this site.
And if so, if you'd like to follow my tweets, might you DM or @me with "follow me back"?