you can use it for centralised authentication -> only for mac, if you have windows or other type machine, just forget it. you can use it for VPN services -> it is not hard to find a router do it more securer and faster, because when the DNS server down, you cannot do anything about it you can run time machine backups to it -> yes, but you also run on a network driver, more efficient you can run web pages off it -> the apache server is nothing improve from the standard, just a standard server, same as xampp you can run podcasts off it -> again many free server and better than this you can share files off it -> all mac os can do it, you don't need a server you can run a wiki on it -> there are many free wiki server with a better interface you can run email on it -> linux has the same function and microsoft much better I have very bad experience with this server - lack of support and simply not linking to the real world But for home / small business use it could be handy. Is it ideal for a 60,000+ employee enterprise? Of course not.

I currently have a mid 07 spec mini running lion server as a time machine backup destination for my GF's MBA 11', VPN server so i can connect back to my home network and desktop sharing so i can leave it running torrents using transmission/transmission web server. If you don't need/want to do any of that it is pretty pointless.

If i need to reinstall i just ensure time machine is current, boot from network and reinstall from my mini. I have the lion install.esd image set up to network boot off my mini. you can use it for network boot/install of OS X on your machine machine you can use it as a log host for your network devices you can use it for centralised authentication

How to use apple server os