Jabber on totalueberwachung.de
I finally configured my local jabber server for multiple domains. And the whole procedure was really painless, too. I just followed the instructions on: http://www.jms1.net/jabberd2/
My previous domain, thebe.orbit.homelinux.net, will still remain active in parallel to totalueberwachung.de as there are quite some people registered (mostly friends and their friends) and I don't want to force anyone to switch, especially since migrating the contact list is not trivial.
Anyone can join that server, so if you are in need of a jabber account feel free.