RUSA Machine-Assisted Reference Section (MARS) The Machine-Assisted Reference Section (MARS) of the Reference and User Services Association (RUSA) appointed an ad hoc task force at the American Library Association's 1998 Annual Conference to develop a method of recognizing outstanding reference sites on the World Wide Web. The task force became a formal committee at the American Library Association's 2001 Annual Conference. This is the fourth MARS Best Free Reference Web Sites list produced by the group. Past lists and all future MARS Best lists will be published in each year's fall issue of Reference & User Services Quarterly. Since the Web is a changing world, readers should note that the Web sites were as annotated on the date the member reviewed the site. Reviewing previous lists is not part of the charge of the committee. Once again, the committee considered sites in all subject areas, selecting only free sites that meet the definition of ready reference and that would be of value in all types of libraries. The committee members felt it was appropriate to exclude fee-based sites. Fee-based services involve many access and collection management issues beyond the scope of this project. These issues include limited access to our user audience and also the logistical problems in obtaining trial subscriptions that would delay the publication of this work. The committee has established the following criteria for nominated Web sites: 1. Quality, depth, and usefulness of content * Clear statement of the content, including any intended biases * Appropriate for the intended audience * Provides appropriate links to other Web sites * Attention to detail; absence of grammatical errors, etc. 2. Ready Reference; usefulness for reference to answer specific questions * May also give a broad perspective of a particular subject 3. Uniqueness of content * Uniqueness of the resource as a whole; creativity * Useful in a variety of reference settings 4. Currency of content * Links are kept up-to-date * Update frequency is appropriate for the subject matter 5. Authority of producer * Authority and legality clearly stated * If not easily recognizable, an explanation of the history and purpose of the organization 6. Ease of use * User-friendly design; easy navigation * Good search engine * Attractive; graphic design leaves a good impression on the user * Easy output (printing or downloading) 7. Customer service * Contacts are responsive; email addresses are correct 8. Efficiency (Note: Because efficiency is affected by the user's method of Internet access--dial-up access, for example, will no doubt be less efficient for all sites--evaluators endeavored to take such differences into account.) * Graphics load quickly or are not so intensive as to seriously degrade access. * Any required plug-ins are available for easy download * Reliable, speedy server; information is there when needed. 9. Appropriate use of the Web as a medium * Components are well integrated (audio, video, text) * Useful information is still available, even if the user does not have ali the plugins and media components. * Effective use of Java and other newer technologies As in previous years, the committee worked virtually, and the process went smoothly, especially since many of the members were returning for a third or fourth year. Each member of the committee nominated and annotated five to ten sites using the criteria specified above. The committee members then reviewed the annotated nominations and voted for their favorite sites. Previous year's winners were not eligible for this year's list, but a site that did not win previously could be renominated. …