This is a case study of how you can use Web Services to access information from another web application in your own blog.
Flickr have an application called the Flickr API Explorer where you can put together a URL to call up the Web Service.
The API garden have a list of the available methods, which you can choose and then you can use the application to put together the correct URL.
This is the URL I put together to get a list of photos from a specific set using the flickr.photosets.getPhoto method:
I have used this information to display these images on my own blog. In reality I could write some XSLT and display them any way I want but in this case I have cheated and used wordpress and the SimpleFlickr plugin to display the photos in a blog post.