Say I would like to follow the events of my local art gallery and the local gigs of a certain musician. The gallery and musician could put out a feed which I could follow, with values including date-time, address, info-url, ticket-url, details. My event-feed reader would pull in the gallery's and musician's events from their website, and populate a calendar with them. Moreover, I could set the reader to only display events in the region I care about, so the only gigs of the musician that would appear would be the ones when they come to my town.
They seems a simple, decentralised way of following events, but I'm surprised nothing like this already exists?