Amen.

A swift, deft dissection of a popular factoid at Insane Troll Logic:

The Pelopenesian War? Economic motives
The Trojan War? A woman
The Napoleanic Wars? Land
The Revolutionary War? Land/freedom
The Crimean War? Who the Hell knows
The American Civil War? Federalism/economics/slavery
World War I? Strange alliances, land
World War II? Land, alliances
Korean War? Civil War, ideology
Vietnam War? Civil War, ideology
The Persian Gulf War? Alliances, land, oil