Getty Images has just announced an embed function, which makes it possible to very easily use images from their collections in blogs and other social media, while simultaneously maintaining Getty Images' rights and -- this is the really nice bit -- avoiding the use of unsightly watermarks. This is rightly being greeted with enthusiasm (though not so much by photographers), and I'll try to use it myself where possible. Even a quick search turns up many great historical images, some familiar, most not. (Basic tip -- to filter out stock photos, restrict your search to editorial images.)
But there are problems, too. Above is an example of a embed from Getty Images. It's from a lithograph by W. Walton of Day & Haghe, lithographers to the Queen, depicting 'Ariel, the first carriage of the Aerial Transit Company', and printed on 26 March 1843 by Ackermann & Co., Strand, London. But the only part of all that which is given in the Getty Images metadata is the title; the rest came from the Library of Congress's copy, which moreover has no usage restrictions at all (since it's long out of copyright) and shows the uncropped lithograph (admittedly, probably less desirable for a blog post). The only other information offered by Getty Images is that the date it was created was 1 January 1900, which is ludicrously incorrect.
We can't expect Getty Images to thoroughly research every image they hold, and an aeroplane flying over Egypt in the mid-19th century is kind of weird to begin with. But the problem of poor or incorrect Getty Images metadata is actually quite common.