As Constantin suggested, here is a list of services, which my home server should provide:

• Personal Video Recorder: I'm using the EyeTV Hard- and Software from Elgato to record, cut and archive TV broadcasts.
• Secure File Archive/Backup: I want my digital camera photos and other precious files to be stored at serveral places and to be protected with checksums.
• A/V Media Server: I want to store my MP3 files and the videos from the above PVR to be stored an be served to clients in the local LAN but not to the Internet.
• Web Hosting: I want to run web application at home. Usually, I'm hosting my webapps at Host Europe, but there are some apps which I can't or don't want to host there. This includes PHP and JEE applications with MySQL as database.
• LAN Gateway: I want to sercurely log into the LAN via SSH and transfer files from and to the server.
• I had also a “OpenSolaris Sandbox” on this list, but I think that one is served bettes as a VirtualBox on my Laptop than on my home server.
• to be continued…: There will be more requirements in the future, like hosting my own Jabber server.

The server will continue to run Mac OS X and OpenSolaris, as the first goal on the above list requires Mac OS X and I haven't found an acceptable PVR solution for OpenSolaris yet. This is currently done using an Mac mini with Mac OS X and running an virtualized OpenSolaris on top of it. In the future, there may be two distinct servers due to some limitations of this constellation (e.g. having to stop the OpenSolaris server to install Mac OS X patches).