SiteSucker is a Mac application that automatically downloads websites from the Internet. It does this by asynchronously copying the site's web pages, images, PDFs, style sheets, and other files to your local hard drive, duplicating the site's directory structure.
SiteSucker can be used to make local copies of websites. By default, SiteSucker "localizes" the files it downloads, allowing you to browse a site offline, but it can also download sites without modification.