Adding your own Certificate Authority to your Debian-like System
Just place it in ~~a custom subdirectory in /usr/share/ca-certificates~~ /usr/local/share/ca-certificates and then run dpkg-reconfigure ca-certificates and you're done.
Did this on a Ubuntu 10.04 System but should work on every up to date Debian-alike System.
To create your own CA you might want to take a look at xca
Edit, Nov 13 2011: I just found out that you should place your own CAs
Also, I found the command update-ca-certificates which adds all new
certificates without a dialog, not sure about this one though.
Edit, Apr 22 2012: Confirmed it working in Arch Linux the exactly same way.