@sakhi,
I definitely agree with everyone here that the "go out door, play with other kids who are there" model is the best one. But if the kids aren't there? Then what?
'Cause that's what we're faced with. If sozlet just hangs out in the vicinity of the house, in plain sight, nothing happens (we've tried it many times). If sozlet goes and knocks on the doors of likely playmates, they're not home. If sozlet goes to the park, that sometimes works, and we do that. But it often doesn't work. (Nobody there, mostly.)
And she has FRIENDS from school she wants to see, as well, and playdates are just the best solution to that problem and the others mentioned above.
She does have a wide variety of friends -- rich, poor, those who don't speak English (at least when they met, now he speaks a lot more), etc. But yeah, they get together in pre-arranged ways, most of the time.
There just aren't that many other options. AND, I don't think it's that nefarious.
Once they get together (in pairs or in groups) they have free reign, and just do whatever. I don't watch over them or give them activities or otherwise schedule their time once they're here. They just goof around in patented kid fashion.
I do struggle with the free range kids part, when it comes to venturing further than our block. I think the kid's ready for a lot more than her dad does, and we have an ongoing debate about that. I talk to parents of her friends about what they let their kids do, and they tend to be more in line with my husband. But I think we're getting closer and closer to the age where everyone's comfortable with a lot more freedom. Older kids (about 10 and up) are very free range here, riding bikes and meandering around in unescorted packs, and I'm definitely looking forward to that.