Software

Site-capturing software (also know as site-whacking software or site-sucking software)
allows you to download entire websites to your computer.

These locally captured sites can be used for presentations where no internet connection is available,
or for storing entire sites on school intranets, guaranteeing availability when required for class activities.

This can also make web sites available to local network users without requiring authentication to the Internet.

WebWhacker (Win)

A 30 day demo is available.

SiteSucker (Mac)

Uncrippled shareware.

Web Devil (Mac)

A free demo is available.

Simplewget (Mac)

Basic (but free) whacking software for Mac OS X.

WebZip (Win)

Another popular "whacking" application. (Shareware).

WebDumper (Mac/Win)

30 day demo available.

Blue Crab (Mac)

30 day demo available.

DeepVacuum (Mac)

Shareware. Doesn't appear to have a "depth" limit for target sites though.

WebCopier (Mac/Win)

Also available for PocketPC.

HTTrack (Lin/Win - maybe Mac)

A free (GPL, libre/free software) and easy-to-use offline browser utility. HTTrack can also update an existing mirrored site, and resume interrupted downloads.