This leave me with an interesting problem. There are a bunch of people here on livejournal who I am sure I must know. At least I think I must know them. These are people who seem to be good friends of my friends, and involved in the sorts of things that I was involved in at MIT, etc. Sadly, I don't know for sure because I just don't have enough information.
I've helpfully put my first name and a picture of me in a big hat on my blog. I'm pretty sure that people can tell if they know me or not. On the other hand, other people have not done this, which makes it much harder to tell. I can understand why they haven't done this, different people have different comfort levels with revealing personal information online, and there are some people who don't like the way they look in a big hat. Also, some people have given their first name, but its less helpful than you might think. I think I know at least a dozen Mikes, two dozen Daves, and a score of Jennifers, so I'm often a bit confused about which particular Mike, Dave or Jen it might be.
So, if you think I've ignoring you by not putting you on my friends list, its most likely because I haven't figured out who you are. You should drop me some sort of large hint so that I a) know you exist on livejournal and b) can figure out who you are.