PDF Clown - PDF Clown is an open-source general-purpose library for manipulating PDF documents through multiple abstraction layers, rigorously adhering to PDF 1.7 Specification
Quick Merge for Excel+Word - Quick Merge for Excel™+Word™ for easy and fast creation of mail merge documents without the cumbersome procedure of inserting {MERGEFIELD} formula.
Document .Net - Gives you API to do everything with a document in PDF, DOCX, DOC, RTF, HTML and Text formats.
jOfficeConvert - Use jOfficeConvert Java PDF SDK to convert MS Word and Excel documents to PDF or images, or print documents automatically from your Java applications.
PDFSharp - Office & Productivity and Development
JSignPdf - JSignPdf is a Java application which adds digital signatures to PDF documents.