[plug] how to add a package cache for debian/ubuntu

[Mike Holland]

good morning, I was wondering:
How do you arrange for apt-get to look in a local directory for .deb 
files, to reduce downloads?
   Two examples:
- updating when another machine on the LAN has already updated, and has 
most of the /deb files we need in its /var/cache/apt/archives
- I want to install mythbuntu-desktop, and have an ISO of the mythbuntu 
distro.

I found that just copying all the .debs from one machine to another's 
/var/cache/apt/archives seems to work, but whats the proper way?