Keryx

Keryx is a python application to easy the time consuming and complicated process of updating the packages and lists on an offline computers. Keryx is essentially a portable version (meaning it can run on a flash drive) and cross platform (runs on Windows, Linux, and Mac) of apt-get and Synaptic. It uses the same algorithms to calculate downloads and upgrades as APT and can therefore download all the packages and the dependencies for offline machines. Being cross-platform, you can use Keryx to download packages for an offline machine anywhere, at work, school, or a friend’s house without any hassle. Keryx is written in Python and wxPython, has been featured in Linux Journal magazine and is released under the GPL.

Homepage: http://keryxproject.org