Melting Metal
instructables - How to Build a Gas Forge Burner
Ron Reil's Home Page
Crucibles for Aluminum
Anvil Fire - Gas Forges
sparkfun - A crash course in aluminum casting
Delft Clay NZ - How to make Refractory Cement 3+ Recipes
Thread: Foundry Tutorial Book
Brian's Metal Casting Project
Adiabatic Flame Temperature

Casting Metal
Gizmology - Making Green Sand
Several sites suggest fine sand and unscented kitty litter, which is made from bentonite clay

Information
Tool Steel Temperature Color Chart
wikipedia: red heat