iText - iText is an intuitive and refined text editor with word processing completely rewritten in Cocoa...
Document .Net - Gives you API to do everything with a document in PDF, DOCX, DOC, RTF, HTML and Text formats.
LibreOffice - Writer - Open-source cross-platform word processor.
PdfPig - Read and extract text and other content from PDFs in C# (port of PDFBox)
JasperReports - JasperReports Server is a stand-alone and embeddable reporting server.
PDFSharp - Office & Productivity and Development