Most of my friends got onto FaceBook for #3, the glorified address book, and stay on it for one of 3 other applications:
2.) Photo-sharing. As of now, it really seems to be the best photo-sharing app on the net.
3.) Making plans to meetup offline or catch up with old friends. This seems to be the most common use of the wall (and to a lesser extent, poke/superpoke), though I gather some other social groups use it for actual silliness.
Flickr is the best photosharing app on the net, without question. I find the intermediary of facebook for photos, even from flickr photos, to be inferior to an rss feed from friend's photos.
My parents are pretty computer illiterate and very active on Flickr. They would be confused by FaceBook.
Real photosharing penetrates demographics where people don't understand computers, not just people who don't understand RSS. My point about RSS is that Flickr is the best for non-technies and techies alike.
What is it about facebook photo sharing that makes it best for you? Is it that the photos of most interest to you are there? Is it a certain point of integration with another facebook feature? Is there a unique feature of their photo sharing function that you like?
1.) They have a pretty good multi-file uploader, so you can take a whole directory of files and upload them at once.
2.) It's free. Many of the other sites with #1 require that you pay for it.
3.) You can tag your friends, and a notification in their news feed will pop up saying they've been tagged in a photo. And all of their friends will see it, usually leading to tags for people you don't know.
4.) Enough of my friends are on it that #3 is useful.
A lot of this is network effects - I think Flickr has all of the above, though some may be premium features. But FaceBook has a critical mass of people that check it regularly, which makes 3 & 4 a lot more useful. If I post to Flickr and tag my friends (can I do that?), there's no guarantee they'll see it.
The tagging makes it the best. The whole low-resolution thing makes artistic photos not work out too well, but for pictures containing people, Facebook really is the best. Especially if you're in college, in which case nearly everyone has a fb account.
This post and this article(1) by Clay Shirky should be required reading for anyone building socially-oriented software.
1) http://www.shirky.com/writings/group_enemy.html Old news to some I guess - but I just found it via a link nostrademons posted in a different thread and it was the most interesting thing I've read all week.
That's a great consolidation of the features offered by typical software in the 'social network' category.
It might also be worthwhile to distinguish the 'network effect' or 'network lock-in' which is when significant parts of the value of a service come from the people already using it.
That's a good point. Even after FriendFeed destroys the network lock-in of the current crop of social networking sites, it's important for people to remember what network lock-in is, to look out for it in the future.
2.) Photo-sharing. As of now, it really seems to be the best photo-sharing app on the net.
3.) Making plans to meetup offline or catch up with old friends. This seems to be the most common use of the wall (and to a lesser extent, poke/superpoke), though I gather some other social groups use it for actual silliness.
4.) Scrabble.