Recently, I discovered a feature in iMessage (I’m speaking of the iPhone version here, though it’s likely true elsewhere as well) that you might find handy, too.
You know how time stamps get dropped into a conversation every so often, but that sometimes it’s not often enough and you just want to see exactly when one of the messages in the thread was sent? iMessage does actually log this information, and all it takes is a quick swipe of the finger to see it. Instead of swiping your finger from left to right (which returns you back to the main Messages screen), you swipe-and-hold your finger from the right to reveal a timestamp next to every message. This works on regular text conversations, too, not just iMessages.