I found iText when I was looking for something else. This let's you write PDFs from within Java. VERY COOL! I know I will be using this!
Easy to install. I downloaded itextpdf-5.3.5.jar, copied it to my WEB-INF/lib, copied a sample program from the website (see links for "iText in Action" book for source code), compiled, and ran. Bam! First PDF from a Java program.
I ordered "iText in Action" from Amazon. About $20 for a used book.