Interesting information on Ritalin:

http://www.researchmatters.harvard.edu/story.php?article_id=8

http://www.mythos.com/pharmacy/detail.aspx?I=568&BM=568&SP=Index_DrugName.aspx&P=1&L=A

How it works:
http://www.bnl.gov/bnlweb/pubaf/pr/2001/bnlpr011501a.html

http://laofamily.org/health/drugs/ritalin.jpg