Getting images from NASA always was an exciting thing there are so many fantastic images in the public domain available from NASA … but up to now on many different NASA sites.
On the new NASAImages.org website, 21 archives are combined in one which will be integrated in the NASA website more and more seemless over time.
The new Image archive will contain historic and recent audio and video material and will be a huge supply of imaginery.
The site is not run directly by NASA but is a cooperation with the non-profit Internet Archive.
Source: Information World Review
Many people who visit this site are searching for pictures of earth from space.
Well, obviously there is no better source for that than NASA. Because this is so hugely popular, NASA has made a own site for that under the slightly cryptic name of : http://earth.jsc.nasa.gov/sseop/efs/
Here you can find all sorts of images of our beautiful planet. And what is best, almost all material from NASA is public domain, that means you are allowed to use it for your own purposes as long as you state the source of the pictures.
Another excellent NASA source for pictures of earth and pictures of space exploration in genereal is
GRIN - GReat Images in Nasa
There you will find such treasures as this one and a lot more:
Have you noticed the pictures on the sidebar? Every day you can see a new astronomy related picture - it can be pictures of outer space, pictures of stars, pictures of galaxies, or pictures of big telescopes on earth. Whatever it is, it is alway a truely fascinating astronomy picture. How is it done? Can you have it on your page, too? Well, yes! It is easy, if you run a wordpress blog. The pictures on the sidebar are from Paul Lamb’s fantastic wordpress plugin APOD. It takes the “Astronomy Picture of the Day” from NASA’s web page (http://antwrp.gsfc.nasa.gov/apod/). Each day a new image is displayed and if you click on the picture, you are taken to NASA’s picture of the day page where you see the astronomy picture in big 
(And where you can read a short description by a professional astronomer, who tells you what you actually can see on the pictures).
If you like space pictures, then the NASA astronomy picture of the day is definitly made for you…
And if you want to explore more pictures of our universe, have a look at the NASA image archive…
