Flickr is a wonderful photo hosting service, and one that I’ve been an active member of for almost six years now (and a paid-up member for almost as long). One of the great things that it made popular was the ability to ‘tag’ photos, as a way of easily grouping photos of a similar topic taken by many different people.
Soon after, some people started adding latitude and longitude co-ordinates to their photographs. Eventually Flickr introduced a proper way to add location information to photos, but were nice enough to use the information from these geolocation tags. These became known as ‘Machine Tags’, i.e. tags that add metadata to a photo rather than describe it in a way that is easily readable by humans.
Since then, Machine Tags have been expanded, but documentation of this is poor. As it happens, you can add machine tags to a photograph which in turn will link it to a whole range of external web sites.
Along with Flickr, Upcoming was another Yahoo! acquisition. If you took a photo at an event listed on Upcoming, you can add the tag upcoming:event=ID where the ID is the 6-digit event ID in the URL.
Alternatively, if the event you took photographs of was a gig or music festival list on last,fm, add lastfm:event=ID; again, the ID is the number of the event. If you can find the event on last.fm, such as the Bingley Music Live page, it will give you the code to paste into the tag box for your pictures. Then, any pictures you take will appear on the last.fm page for that event.
Not having a smartphone means I haven’t yet used Foursquare, but if you have taken some pictures at a venue and have its ID, add foursquare:venue=ID. For an example, here are my Bingley Music Live pictures tagged by Foursquare ID.
OpenStreetMap points of interest
If the thing you have taken a picture of exists as a point of interest on OpenStreetMap, and you can find its ID number, add osm:node=ID as a tag.
If you’ve taken a picture of a restaurant, or a hotel, or an interesting landmark, and it’s listed on Dopplr (a bit like TripAdvisor but with more social features), then you can tag it. Use the codes from Dopplr’s Social Atlas to add the correct code. The pictures you tag will then appear on Dopplr!
Open Plaque blue plaque photographs
Across the UK, we use Blue plaques to highlight buildings of historical significance. Sometimes it’s a simple case that a famous author or politician was born there. OpenPlaques is trying to get pictures of all of them, so if you have a picture and want it adding, add openplaques:id=ID to your picture’s tag.
Open Library book covers
If you’ve taken a picture of the cover of a book, add openlibrary:id=ID to it, where the ID is the number of the book from the Open Library web site.
There’s probably more than those that I have mentioned. As they’re not well documented, few people know about them or use them, which is a shame as it makes Flickr a lot more useful. Hopefully a future version of the Flickr Uploadr may add features that allow relevant machine tags to be added more easily.