The battle of Cynoscephalae in 197BC pitted Greek phalanxes against Roman legions. This scenario recreates that battle for the Vis Bellica rules set.
Ancient Battlefields is a set of free wargames rules "with an emphasis on Command and Control". The game is over when the opposing general flees the field.
The Illustrated History of the Roman Empire website is just that — a neat historical site with loads of pictures and interactive map. There is lots of fodder here for historical wargamers.
Tom’s Ancient Warfare Rules is a set of free wargames rules for the ancient period.
Imagine Image offers the freeHex Command Ancients Rules for miniatures wargames. The hex system is supposed to simplify things and speed play. You can play without a hex board if you want.