HubbleSite - Picture Album
Hubble telescope images. A lot of them!!!!
The super high resolution available on some photos will need resized smaller. They warn you which ones might effect memory usage. I'd take the smaller of the high res and resize for your screen if the standard sized are to small.
This pic is 1.53MB a perfect size. Click this pic and click the window that opens then click the second window that opens.
I liked that one so much I'm using it myself.