There have been numerous times in the past where I was asked about joining facebook, but didn't. Eventually I caved in about August last year, and I have to admit to being quite addicted to it.
I probably average 4 status updates a week (generally meaningless or trying to be witty comments), but AM interested in seeing what responses (if any) I get to those, or just if they are 'liked.'
I haven't bothered tying to get too many friends though and currently have just 35. One of these seems to be on there almost every time that I log on, which is on most days.
To scroll through your news updates occasionally can be relatively entertaining. I think it's a matter of restricting your time on FB - as people have said, having some self control.
I was in a relationship a little while ago and the daughter of the woman I was seeing totally cracked it at me once and posted on my wall, which was a good example of the problems that FB can cause. Although the relationship ended, her post didn't cause any actual problems because later that day she deleted me as a friend and this removed the post.
I realise now that I could have deleted it myself too!
Yes, FB can be a waste of time. But if I wasn't on FB maybe I'd just be wasting my time anyway? Letsrun is a little more interesting because people can make lengthy posts, but people can and do still spend a lot of time on here (I went through a phase in 2007 when I was reading stuff on here daily, but have largely disappeared since then apart from perhaps a glance every month or two). The internet in general can help greatly in improving people's knowledge of basically anything, but it is filled with things that can be considered time wasting, such as anything to do with masturbation. And is this post a waste of my time? And is the brief time that I take to check for any responses to it a waste of time too?
As has been pretty much summed up by about the first half of posts that I've read, Facebook can be a postive and a negative. The key is not to spend too much time on it.