iOS: Twitter is a great feed, but saving interesting tweets for later, making playlists of songs you find and collecting interesting or on-topic tweets into lists is difficult, and deserves more than a "favourite" button. That's where Charm comes in -- it makes all of that super easy. Frankly, Charm is the kind of tool that Twitter should roll into the official app. Think of it like Twitter lists, just for everything or anything you want, not just for people. It's iPhone only (which is a shame, maybe it will come to Android soon) but you can use it to build a playlist of all of the music your favourite musicians and music accounts have posted, or maybe someone's in the middle of a massive tweetstorm you want to read later, but you want an easy way to parse through it without going to their profile or faving everything. Charm can build that playlist for you, or save all of those tweets.
Charm can also be your personal twitter repository, so you can hold on to hilarious jokes people have told, users you're interested in but don't want to follow, or even just automatically snag tweets from events you're following, like a Game of Thrones night, or the Olympics. Best of all, it works with the Twitter apps you already use, whether that's the native Twitter client, Twitterific, Tweetbot, the actual Twitter mobile web site or some other client. It even works with OS X's Handoff feature so you can open your saved collections on your desktop, so you're not limited to just your phone's screen.
Hit the homepage below to learn more and see some examples of the collections it can make, and the app store link to give it a try.