Relating to the compositing techniques sub thread:

Two extremely good books on the topic are: "ILM Journal. The Art of Special Effects", and its newer counter-part "Into the Digital Realm". While being a showcase of the work of the Lucasfilm Company ILM, they go into a great deal of explanation of the process. They also use well-known scenes from familiar effects films to demonstrate what is being explained.

Cheers,
Dwight