I have used the Apache FOP project to create PDFs in a servlet environment. According to this page the TIFF format is supported by FOP to some extent. According to this page, the popular iText toolkit supports TIFF graphics.
I suggest your first step should be getting a TIFF to PDF conversion working in a stand-alone application.
Bill [ March 13, 2007: Message edited by: William Brogden ]
TIFF is the standard image encoding scheme in PostScript, and PDF is a specialized type of PostScript. So if you are so inclined, you can take a TIFF, wrap it with the appropriate surrounding data, and emerge as a PDF.
Which is a pretty straightforward job for a servlet. You probably could do it as a JSP without too much trouble.
Sometimes the only way things ever got fixed is because people became uncomfortable.