FxPDF is a rewritten in Action Script 3.0(AS3) original libHaru PDF library project developed in C language.
It is generating PDF files on client side by using native Action Script code in Adobe Flex and Adobe AIR projects.
If you want to have a test, please follow the FxPDF Examples
For details, please visit here.

Swf2XNA is an open source program under BSD license, developed in C#, with it , you can make Windows/XBox/Win7 games by leveraging Flash for assets and layout, as well as using Box2D visually. It makes 2D games in XNA quite simple to make!
Download source code here.

P.S.
About XNA
Microsoft® XNA™ is composed of industry-leading software, services, resources, and communities focused on enabling game developers to be successful on Microsoft gaming platforms.

Xournal is an application for notetaking, sketching, keeping a journal using a stylus. It is free software (GNU GPL) and runs on Linux (recent distributions) and other GTK+/Gnome platforms (also support Windows now).
It is similar to Microsoft Windows Journal or to other alternatives such as Jarnal, Gournal, and NoteLab.
Xournal supports annotates PDF(render/import PDF) and export annotated PDF.

It uses libpoppler to render/import PDF, and uses poppler-glib to create Annotated PDF, but it is a pity that it convert the original PDF to image version PDF.