The Islamic Manuscripts Association (TIMA) is an international not for profit organization based in the U.K. "dedicated to protecting Islamic manuscript collections and supporting those who work with them." As such, TIMA provides a wide variety of online resources about manuscripts and their preservation, and most importantly offers yearly a workshop on codicology.
Islamic Manuscripts Basics is a site designed for self-teaching the basics of Islamic manuscripts (Basics, Binding, Substrate, Layout, Scripts, Decoration, Notes) created by Dr. Kelly Tuttle, cataloger for the Manuscripts of the Muslim World Project hosted at the University of Pennsylvania Libraries.
Miniature Painting, Calligraphy & Other Book Arts by Amanda Hanoosh Steinberg at Harvard Library
Resources for the study of manuscripts produced in the Islamic world and the manuscript cultures they represent by Evyn Kropf at the University of Michigan