OpenURL resolvers and federated search engines are important new services in the library field. For some librarians, these services may seem "old hat" by now, but for the majority these services are still in the early stages of implementation or planning. In many cases, these two services are offered as a seamlessly integrated whole. That is, it is not really clear where one ends and the other begins. To some degree this decision may be driven by the model your software vendor uses to implement the services. Tight integration generally means an implementation with a "big bang" whereas looser integration allows the library to stage the introduction of the services. In either case, the same basic usability-related issues will arise. It is critical for librarians to make sure that these services work--from the patron's perspective. They represent extensions of the library that further enable people to find their own information, which will be critical to the library of the future. The author of this article, the assistant university librarian for information technology at Northwestern University in Evanston, Illinois, describes a program of usability testing that has been in place for the library's main Web site for over three years. It has allowed testing of various aspects of their Web site and the library's catalog.