Using apt-cacher-ng here on Squeeze, tried the others and found that the 
most reliable. Like the alternatives (apt-move, approx..., ) caches what 
you download during apt-get/aptitude operation to a "repo-image" format. 
Is very much self-maintaining once set up and works well as an apt 
server.on LAN

Certainly earned it's keep here while main mirrors were down recently

To mirror the whole lot... it's rather large!

David