Apt-proxy automatically builds a debian http mirror based on requests which pass through the proxy. it's great for multiple debian machines on the same network with a slower internet link.
the archive is automatically kept up to date using http, ftp or rsync. cache cleaning of unused and old versions is configurable. you can also import the contents of your apt cache into the archive using apt-proxy-import.
the suggested packages are needed for the following features: rsync for rsyncd backends, and dpkg-dev for apt-proxy-import.