Photographers and anyone else with loads of images (or any other form of digital media for that matter) on the internet and in particular on social media sites, should take heed of the recent Instragram terms of service mess as this kind of "greed" is now coming from unlikely places...
The UK government (in particular the Conservative / LibDem coalition) is about to introduce legislation (the Business and Enterprise Reform Bill) that would automatically opt your "orphaned" work into what they call a "extended collective licensing" scheme where it could be used for commercial exploitation. Basically if your image doesn't include your name in the metadata (which can easily happen), it can be classified as "orphan works". In reality a company or individual could copy your images from the internet and if it doesn't include your name or explicit copyright information, it could use it without risk and without compensating or recognising the creator. The new law will explicitly protect these companies and not the creator of the images under the auspice of "making it easier to trade on the internet".
There is an alternative. It is called Digital Rights exchange - a type of "copy right hub" - and it would allow image creators to deposit their work to the hub for others to use. It's almost like an iTunes for images, but it would link up existing and future exchanges of all digital media - not just images.
Act quickly people, the government is currently rushing the new legislation through Parliament before the European orphan works law preventing it kick into action.
WHAT YOU CAN DO:
Write to your MPs and urge them to vote against it. The photography industry is already in turmoil due to the deflation of image prices - this change would be a death blow for many in the photography industry.
What the big players are doing:
Progress of the bill: