If you’ve got a page, which is based on some CMS, Wiki, Blog or else, but which you want to keep online for the sake of history only, you can use wget to create a static copy of that page, removing any dynamic code, which saves you the hassle of updating the underlying system.

Here is an example for mirroring the domain example.com into the directory /home/you/example.com:

wget -nc -nH -E -r -k -P /home/you/example.com -np http://example.com/

wget will save all pages with an .html extension and adapt the links in every page to the new structure. The only problem I had were missing images referenced from CSS files, but you can simply copy those manually.