Mashups are websites that have built on the foundation of larger, more robust web services. For example, if you wanted to sell books online, you could build a website that would tie into Amazon's immense data through its Application Programming Interface(API). In recent months, these Mashups have grown tremendously and often serve very useful functions. ProgrammableWeb is a directory of Mashups. I recommend you take a moment or two to look around the site. It has some jewels that might be very useful to your patrons.