[openfuture]

I don't think you could have this without it devolving into what is essentially a religious debate but I'd be very interested in a collaboratively built wiki of age appropriate challenges or documenting developmental milestones vs skills they unlock (similar to tropes vs stories on tvtropes)

For example I've heard kids can go to school when they can reach the ear on the opposite side by reaching their arm over the head. Also at some age they start to understand non-literal meaning i.e. sarcasm but until then they are oblivious. This would be very useful knowledge to concentrate into a wiki.