It's finally easy to take photos/videos via camera or get photos/videos from gallery on Android. No more dealing with ContentResolvers, Intents, Uris when taking pictures/videos or getting photos/videos in an Android app.
Share your daily life with the world. Send out tweets when you exercise, sleep, work, etc to keep you held accountable.
Twitter bot that watches for certain tweets and replies to them. I ran this in production once to sell t-shirts. The bot got banned from Twitter within hours.