Flickr Machine Tags

Today I was uploading pictures to Flickr from a concert I attended last night and found out that I can put what Flickr calls "machine tags" on my pictures to link them to other services (in my case Upcoming and Last.fm).  These have been around since 2007, but I had never heard of them.  Why aren't we using these handy things for our events and conferences?  Is anyone using Flickr machine tags?

See what it looks like when you use them (look under the copyright):

Clicking the links next to "Taken at" will take you to the event information on Upcoming & Last.fm.  Very cool!