I think one of the best things Facebook can do is let you untag pictures. Pictures that don't make you look like yourself, pictures where you're doing things you wouldn't want your mom to see, or, in my case, pictures that make you look FAT. I go through my Facebook photos from time to time and sometimes have a hard time distinguishing what I look like now (down 45lbs) from what I looked like then. There are some obvious changes. I've clearly lost weight in my face (no double chin anymore!). But beyond that, I have a hard time understanding how different I look. Compared to the last time I lost weight, people have been making relatively little fuss about the changes I'm making. So while last time I really felt MUCH thinner, I don't really have that same sense of it all right now (even though I'm pounds away from my lowest weight in recent memory).
I saw one picture of me in a friend's album from last summer. And somehow it hit me that I didn't like many of the other pictures in that album. But, of course, only one picture was tagged. So I went through the album and, lo and behold, I found this picture: