I use iStockphoto for images and get their Tip of the Week. Today it says:
LIFE and Getty Images, the two most recognized names in photography, have created LIFE.com so you can access millions of breathtaking photographs — for free.
LIFE.com lets you wander through the legendary LIFE and Getty archives, and with more than 3,000 new photos added every day, it also gives you the best pictures of people and places shaping our world.
I have taken a look at the new LIFE – Your World in Pictures and it looks very promising.