PDF Writers?

Saqib Ali asks: "I am looking for for some OpenSource PDF Writers/Creator. I found one, here. It can basically create PDFs out of common software Like OfficeSuite, Visio, Project or any other Windows Application that uses the Windows Printers. I know OpenOffice can also export to PDF. I am working on a project (fat client) where I need to dynamically create PDF reports from data stored in MySQL DB. I know I can use PHP to create PDFs, and also Apache's Cocoon (you can find an example document, here). Of course, I would like to investigate other OpenSource PDF writers as well. Do you know of any other PDF writers, that I can utilize or learn from by looking at the source-code?"