Wargames

http://en.wikipedia.org/wiki/Wargaming#Computer_wargaming

Free Wargames
http://www.dhq.nu/freewargames/

Spaceship games
http://zappa.brainiac.com/spaceship/spacewww.html

I'm investigating
SUPERPOWER CLASSIC
http://itake.se/spclassic/index.php?act=boardrules
(seems this game isn't active atm)
Q pawn
http://s11.invisionfree.com/QPAWN/index.php?showtopic=1

I just downloaded

Advanced Strategic Command
http://www.asc-hq.org/