"Twitsper drastically changes the Twitter experience.
You can say, hey, I only want my closest friends to see this tweet. And this one's about sports, so I only want my sports buddies to see that one. And this tweet is a work-related inside joke, so I only want my work colleagues to see it.
You do this on Twitsper through pre-set lists. The creator and others on the list have the ability to send tweets back and forth that only they can see by using the app, which the developers hope will one day be integrated into Twitter itself."