Still looking for a reason to use Facebook's now-unbundled Messenger app? A new feature learns from competition including Snapchat and Facebook's own Slingshot by adding easy annotation on shared photos. Just click the picture icon like you normally do, then hit the edit button instead of send, and you can doodle with your finger (remember Draw Something? Is anyone still playing that?) or just type in some text before sending. Right now the tweak is Android-only, and should already be live if you're running the most recent version of the app.