HTTrack is a freeware under GPL license user friendly offline browser utility for windows, Linux, Unix and BSD.
It helps you to download a Web site from the Internet to a local directory, building recursively all directories, getting HTML, images, and other files from the server to your computer. HTTrack arranges the original site's relative link-structure. Simply open a page of the "mirrored" website in your browser, and you can browse the site from link to link, as if you were viewing it online. HTTrack can also update an existing mirrored site, and resume interrupted downloads. HTTrack is fully configurable, and has an integrated help system.
You can download WinHTTrack for Windows 9x/XP/Vista/Seven or WebHTTrack for Linux/Unix/BSD operating systems.
In order to get HTTrack portable download "httrack-noinst-3.43-7.zip", extract it into a folder fo your choice and run "WinHTTrack.exe".
Enjoy!