Features you want in your favorite SNS?

Do you have any features that you want to be present in your favorite social networking sites? Honestly, in Twitter, I wish to have an "Edit" button similar to Facebook. Sometimes, there are tweets that I tend to overlook when posting it. There are grammatical errors, which are most of time embarrassing. Another is the trending hashtags for Facebook. I just want to see those trending hashtags similar to Twitter in Facebook.