I just checked the memory requirements and while it is bad for running one copy of dominions it doesnt seem too bad for multiples.
http://www.techno-mage.com/~dominion/memstat.txt
I did have more problems earlier but just upgraded to a swapd arrangment which might be helping (daemon to manage swap area on the fly). This information is from a Debian Linux machine.
A server is pushing the information out the port. A server machine doesnt really need a graphic card or sound card that can play the game. It also doesnt need much hard drive, or all that much CPU. But CPU and RAM are the two things that make the most difference in the performance of a server. Unfortunately those are the two most expensive things if you wanted to build one. You can cut back by having minimum video/sound/drives, and no keyboard/mouse/monitor.
If someone wanted to pick up one of the BBS softwares (Bulletin Board System, all-in-one package for web managing web forums, file upload/download, personal Messages between Users, and a news page) then they could probably become a multiple game manager with just that knowledge. The domains of dominions2.net dom2games.net domgames.net dommap.com dommaps.com dom2taw.net dominionist.com dominionism.org are still available if anyone wants them.