HTTrack - HTTrack is a free (GPL, libre/free software) and easy-to-use offline browser utility.
Offline Explorer - MetaProducts Offline Explorer is a Windows NT/2000/XP/2003/Vista program that allows you to...
WebCopy - Cyotek WebCopy is a free tool for copying full or partial websites locally onto your harddisk for offline viewing.
SiteSucker - SiteSucker is a Macintosh application that automatically downloads Web sites from the Internet.
ScrapBook - ScrapBook is a Firefox extension, which helps you to save Web pages and manage the collection.
ArchiveBox - The open-source, self-hosted internet archiving solution