Various sites are set up for kids to go and play, chat, learn, build their own webpages. Some also act like personal organizers. A friend pointing me to Kiddo Net led to me finding that they’re categorized on Google as
Kids and Teens: People and Society: Online Communities
On carpools, all I’m able to find are regional transit sites, like Rideshare Online, not smaller-scale group organizing sites, though there are software makers with scheduling apps for carpools and such.
(FastCompany article from 1999 on organizing busy families but of course, that’s two Internet ages ago… though it does remind me about WatchMe! and other sites that let working parents look in at day care centers, something that seems to have dropped off the meme-dar.)