Siemens Automation Cooperates with Education (SCE) provides tutorial materials on Siemens S7 in the following link:
Animation / Flash
The following is the presentation on Siemens PLCs for begineers:
The following links are a flash animation of Siemens S7 (right click to download):
The following link is the demo for Siemens PCS7 system (right click to download):
s7-300-2342
Books
Several books are available for good sources for studying the Simatic S7 (note That the following links Provide only the sample pages):
books
Master's Thesis
The following link is the Master's Thesis about Siemens S7 application:
The following links are the Master's Thesis about Siemens PCS7 application:
Further References