simplest shadows?

hey,
i was wondering which way is the easiest way to do shadows??

can you point me to the best tutorials?

thanks

Basic shadows: http://www.sgi.com/software/opengl/advanced97/notes/node100.html#SECTION000114100000000000000

Texture shadows: http://www.opengl.org/developers/code/mjktips/TexShadowReflectLight.html

Stencil (soft) shadows: http://nehe.gamedev.net/data/lessons/lesson.asp?lesson=27