This post is over a year old, some of this information may be out of
date.
Document Viewer
http://www.snowbound.com/products/document-viewer
Zoomify
http://www.zoomify.com/default.htm
Prizm Content Connect
http://www.accusoft.com/prizmcontentconnectpricing.htm
Leadtools Document HTML5 Module (USD 3495 and still got server licensing)
http://www.leadtools.com/resources/weborder.htm
jsgraphics
http://www.walterzorn.de/en/jsgraphics/jsgraphics_e.htm
Deja ViewONE
HAT - HTML5 Annotation Tool
https://github.com/thomashuston/HTML5-Annotation-Tool