Subject
Here's an idea for Facebook. Get rid of subject lines in messages. They almost never have any content in them other than "Hi". Nobody ever changes subject lines in threads, because it seems like you're trying too hard, so they're usually unrelated to recent conversation. And it makes it seem like when you're writing to someone, you have to have something to say that can be summarized. But often what people want to say is just one sentence, "Hey, nice to see you last night at the club" or something. There's no short version of that. Getting rid of the Subject: field would lead to a lot more messages since it makes it so much easier.
Typical subject lines contribute nothing:
But two lines of body would have been the whole message.
One of Twitter's virtue's is not requiring a subject line. Even better, it doesn't require a concluding paragraph with a call to action like blog posts are supposed to have.
