Weapons
Links
History of Blowguns
http://www.blowgunsnw.com/history.htm
Blowguns in history, from ancient beginnings to modern usage.
The Onager
http://members.lycos.nl/onager/
Read about the origin of this artifact which was invented by the Romans, and used as anti-personnel weapon and a siege engine.
Catapults.info
Read about different types of catapults, both modern and ancient, how they were used and common misconceptions.