Create a "controlled" APT proxy

Do you have any experience/scrips creating a controlled APT proxy (*)? Currently, I'm using apt-cacher to speed up installs/updates in my LAN, but as its name says, it's only a cache (and a good one for my needs). The only drawback is that I don't know how to freeze a specific set of packages for the cache/repository to control updates. Almost certainly, apt-cacher isn't the right tool for this jobs so, any help would be appreciated.

Thanks in advance,

Humber

(*) An APT repository that has only specific packages and updates to control the OS that uses that repository. I named this way because I don't know if it has another name

You can create your own apt repo with reprepro debian (ubuntu?) package, and then add the repo's url to the sources.list of client boxes.

Reprepro howto: http://www.debian-administration.org/articles/286