SiteCrawler is the first really good site downloader for Mac OS X. It's easy to set up, and offers all the features you need. It's the fastest application of its kind, and it's based on Apple's modern Cocoa framework.
SiteCrawler goes beyond many other similar programs in terms of features. By default, downloaded web pages are modified so that hyperlinks point to files on your hard drive. This means you can browse the downloaded web site without problems with broken links.
SiteCrawler offers advanced features to help you fine-tune which web pages to include. You can prevent certain files from being downloaded based on rules you set up. You can also choose to access some pages that would normally be omitted (based on other settings). Rules can be set up to not save some pages on your hard drive, but still follow the links in them. The possibilities are endless!
SiteCrawler works with all standard HTTP authentication schemes. The passwords are read from your keychain, if available. SiteCrawler also has a unique feature that can use Safari's session cookies. This means that even if the web site you're trying to access is behind a form-based authentication system, you can log in using Safari, and use that session with SiteCrawler.
With SiteCrawler, you can save your session for later use. You can even pause a session while it's downloading, save the session, and continue downloading later!