Plenty of free pics online, but quality is far less common. For flashes of colour amidst the dross, try New Old Stock, Unsplash, British Library on Flickr, NASA on Flickr, the Rijksmuseum and the Google Art Project. Try also Agence Eureka and Bibliodyssey.
360 degree world
Google Street View gives users the chance to 'stand' on any of millions of streets and pan to see the scenery. But as every viewer knows, the average street is pretty prosaic, and the image quality is not fabulous anyway. Which brings us to 360cities. This immersive site has thousands of high resolution 360 degree images from all over the world — views of mountains, canyons, urban scenes, forest glades and massive crowds. The images are seamless, sharp and occupy your full screen with thousands of details that you can absorb at leisure. The interface is easy to navigate, piggybacking on Google maps (and also appearing as a layer in Google Earth), and once you get started, stopping is a problem. Check out some of their ultra high resolution images — the London Eye panorama is a jaw dropping 80 gigapixels.