One of the projects I created a while ago is called “rapt (restricted apt)“. As I was asked about it on irc about recently I thought I should mention it here as well :)
It is a python-apt app that will allow regular users to install/update software or install build-depends via sudo without giving them full root access. rapt will ensure that there is no interaction (like conffile prompts or debconf) that might allow the user to get a rootshell. It allows blacklisting and with a suiteable sources.list it is a easy way to give limited access to more trusted users. One use-case is to allow developers to install build dependencies on a staging machine.
You can install it via
$ bzr branch lp:rapt
and just run the binary via sudo (and a sudoers file that allows to run it). All it needs is python and python-apt (which is installed on most system anyway).