Including somebody else's image in your own web page is legally tricky. The law is in flux on all manner of digital intellectual property rights issues, and web publishers are seeking reasonable practices that won't get them in hot water.
I have checked with some of our local authorities, and I have looked to see what the people at http://news.google.com/ are doing. As a result, I have a standard approach that I think will work for our purposes this term.
To use somebody else's image, make yourself a copy of the image and store the copy in your own web directory (/Accounts/courses/cs107/web-pages/yourname/). Link your page to your copy of the image. And then (this is the important part), provide a link below the image directing the reader to the owner of the image. Here's an example.
To see how I did this, view the source of this page.