If you have to create PDF's then youll probably eventually end up looking at PDF::API2

There are many ways to produce PDF file:

• HTMLDOC - tool for convert HTML pages to the PDF or PS. It's very useful if you need produce print view of some documents using template which should be filled by real data (invoice or receipt, for example)
• FOP - Formatting Objects Processor: print formatter driven by XSL formatting objects (XSL-FO) and output independent formatter, supported include PDF, PCL, PS, SVG, XML, Print, AWT, MIF and TXT.

In my opinion, FOP is good base to develop solution for converting documents. I planning to use FOP for build document module of billing system to produce billing documents, reports etc. Currently, I use HTMLDOC as temporary solution.