I'm not sure if anyone has posted this yet, but I found a series a videos on the making of the two big battle scenes in 1 and 2. They talk a lot about Massive, the program they used to make the 80,000 person armies, and about compositing the final shot.
Behind the Scenes - LOTR
Also they mentioned this really cool scanner that they used to scan the clay model to turn them into digital geometry.
<a href="http://www.metic.net" target="_blank">www.metic.net</a><br />