Here is a fantastic sitte.
http://antwrp.gsfc.nasa.gov/apod/
It is often called APOD (Astronomy Picture of the Day). Astronomers from all over the world submit their work to Nemiroff (a working astronomer and professor in Michigan or Minnesoto)
In the upper left of the screen, there is a link to the index of all APODs and it is very large.
Take a look through
http://antwrp.gsfc.nasa.gov/htmltest/rjn_com.html
for some fun reading about Star Trek, the life of a star. etc.