Not tutes, just communal head-scratching threads, but here's some from long ago on shadow control, and also addressing shadow antialaising and shadows cast by semi-transparent objects, including some sample illustrations.

http://www.renderosity.com/messages.ez?Form.ShowMessage=906924

http://www.renderosity.com/messages.ez?ForumID=12356&Form.ShowMessage=1059682

http://www.renderosity.com/messages.ez?ForumID=12356&Form.ShowMessage=1615561