This is the Debian package repository of koumbit.net. It is used for internal distribution of locally built packages not yet part of Debian. Feel free to use it for yourself, but it comes at no warranty.
In your /etc/apt/source.list:
deb http://debian.koumbit.net/debian stable main deb-src http://debian.koumbit.net/debian stable main
stable can be replaced by
unstable if you wish to test the development version
This archive self-signs packages uploaded to it (and packages uploaded are verified against a whitelist of trusted uploaders) using OpenPGP (GnuPG, to be more precise).
The key of the archive is in the key.asc file. You should add the key using something like this:
wget http://debian.koumbit.net/debian/key.asc apt-key add key.asc apt-get update