Here's some features this tool provide:
1. You can compare all types of units against each other, as well as how many of each unit
2. You can choose which upgrades you may like to have
3. The simulation take care of special bonus damage, i.e: an axeman have 3*damage against a throwing axeman.
4. You can edit/add new units/civs if you like
5. You will see the total cost of units as well as total cost of the techs
Version history: http://users.chello.no/~dgabriel/som/help.html#patch_history