[gorpomon]

This was the original purpose of Twitter-- it was advertised as a network where anyone could post what they're doing and notify their friends immediately. Even until recently tweets could be received via SMS (not sure about the current status of that feature) so you'd see in real time what they're up to.

Of course, Twitter/X/etc are a far cry from that now-- but it could be worth trying where you and your friends use the service like that.