I’ve just started using iTextSharp, a .NET port of the Java iText library. It’s surprisingly good.

The library can create files or streams of PDF. I’m caching my output, so this example uses files:

        // create a document
        Document document = new Document();

        // associate it with a file
        String filepath = Request.MapPath("/Pdfs/test.pdf");
        FileStream file = new FileStream(filepath, FileMode.Create);
        PdfWriter.GetInstance(document, file);

        // write the pdf
        document.Open();
        document.Add(new Paragraph("OMG this thing works"));
        document.Close();