"If you've ever looked into setting up a web cache for your
office or campus, you're probably familiar with Squid. Available
from http://www.squid-cache.org, Squid is a full-featured web proxy
cache licensed under the GNU Public License.
"Squid is often used as a reverse proxy, caching and serving a
site's web pages to reduce demands on its web server... But Squid
is also an effective proxy. By caching popular content--keeping a
copy of remote web pages on a local server--Squid can reduce
bandwidth consumption and serve (cached) web pages faster..."