Shakespeare in "quarto"
HyperHamlet:
the cultural history of Shakespeare's play in quotations
http://www.hyperhamlet.unibas.ch/
HAMLET NAVIGATOR
http://www.shakespeare-navigators.com/hamlet/index.html
Shakespeare Quartos Archive is a digital collection of pre-1642 editions of William Shakespeare's plays
http://www.quartos.org/
Hamlet on the Ramparts
http://shea.mit.edu/ramparts/
Folger Shakespeare Library
http://www.folger.edu/
Royal Shakespeare Company
http://www.rsc.org.uk/
Hamlet Works
http://leoyan.com/global-language.com/ENFOLDED/index.html
The Oxford Text Archive
http://ota.ahds.ac.uk/
Shakespeare Quarterly
http://www.jstor.org/journals/00373222.html