DJW's Metamorphic Petrology: Annotated links to material about metamorphic rocks, migmatites and granitoid rocks, and related areas of "hard-rock" geology.
Phase equilibria in metamorphic rocks - thermodynamic background and petrological applications: Several PDF documents explaining both basic and advanced petrological methods to infer metamorphic pressure-temperature paths.
Skarns and Skarn Deposits: Comprehensive information on an economically important class of metamorphic mineral deposits, with photos and links.
Structural Geology and Metamorphic Petrology on the WWW: Extensive collection of links to Structural Geology and Metamorphic Petrology.