These sites, interesting by themselves, can present a potentially powerful tool for helping people organize.
43things -- what do you want to do with your life.
This site is designed to help people list their goals and post progress on them, through a blog-like interface where you post and others can comment. If you want, you can get notified when people respond directly to one of your posts or comments via email.
You can also invite others to join your goal, and they can either do it with you as a team member, or they can do it on their own. Multiply this to the whole world and you see all sorts of people wanting to do similar things.
The team functionality lacks a bit, and it's purpose in the site seems fuzzy at best. More on this later.
Each goal also has an option for a person to say "I want to do this" or "I've done this already." Users can also post as to whether or not it is worthwhile to pursue that goal in the first place.
Goals can also be tagged with common words to help others find goals of importance to them. Through use of a tag cloud, you can find the most common tags, and by extension, the most common goals of the moment. To find the top 10 goals, all you have to do is click on "Zeitgeist" to see what is the most current goal.
Ok, but so what? (invoking my best Ron Popeil imitation) "But Wait, there's more!"
43people -- who do you want to meet?
Similar to people listing their goals, users can list the people they want to meet. They also have the option of using some stock entry headings such as "Why I want to meet," or "I like so and so because." Anything that is posted about another person has to be approved by that other person to help prevent abuse.
Now what works well here is that 43people can be hooked into 43things. Take for example a goal you have and a person you've met or want to meet. It's possible that the person you've met or want to meet has some connection with one of your goals. They are then essentially a collaborator, or mentor depending on the relationship. Likewise, a person can be a connector to other people if one party met the person someone else wants to meet.
Looping back to 43things briefly, the people you met or want to meet are, by default, in your subscriptions list. This means that rather than searching for each of them individually, you can see all of their recent activity. In a sense, this ties back with the notion of a team goal and ties it up nicely. If they post on a paricular goal you have in common, it will appear on the subscriptions list and on the goal page. In theory the team on 43T should send you notification of a teammate's activity, but I haven't seen that just yet (bug, design, user error?)
43Places -- Where do you want to go?
By now, you have a sense of how these sites work. You list something, others chime in and share thoughts, reflections, etc. It's all tied into your profile across the sites, and can show how your desire (in this case a place to travel to, or a place you've been) relates to another person.
These sites seem to integrate well with existing sites or blogs, so you can list any of these sites (people, places, things) on your own site and keep others up to date as to your progress. Think of it like a Flikr plugin for your site, except these are people, places or things.
How do I see these working together to help bring get people involved? Mostly I think it comes down to people. I like the fact that the goals are all public for the world to see. You have the opportunity to get a glimpse of the person behind the goal. You also have the ability to cheer each other on (a very natural thing to do) to show encouragement. By connecting the people with a goal, and tying them to a location, it would seem there is the potential for action to occur. Sure, it doesn't guarantee it, just as standing next to a stranger on a corner won't make you friends, but it does increase the odds as you (potentiallY) have something in common with one another beyond standing on a street corner.
The role of 43 things, people and places can also help with the notion of critical mass / momentum online. By integrating the information on those sites into blogs, you could get a wide exposure of a particular goal. Additionally, if a concerted effort were used to ensure activity with a particular goal/tag, it could help raise the overall visibility of that goal, essentially drawing in more people.
Of course, it's not a perfect model. Posting of resources or documents is limited to linking a post and tagging it as a resource. Additionally, there doesn't seem to be a way to schedule something or view a calendar of related items in that area. I could see how those would be beneficial in group goal planning, though I also understand why it is not there at the moment. In spite of this, the 43family, by the Robot Co-op, does seem to present potential in helping people and groups acheive their goals. Good job! Can't wait to see what else you have in store for us!