I own a Sony Reader PRS-600 ebook reader. I bought a ton of Manning Publications ebooks (DRM-free) recently. Many of the books are PDFs since not all the ones I wanted are available in epub format.

The problem: Some of the PDF books I purchased have incorrect or missing metadata. Making things worse, the Sony Reader only displays the "Title" from the PDF metadata when displaying book titles in the reader's collection of books! The Reader doesn't display the filename. So, even though I have a PDF informatively named "Windows PowerShell In Action.pdf", it shows up as "untitled" in the Reader.

Imagine how useful the Reader's list of book titles becomes when many are just "untitled" or "unnamed document" ! Yes, it is maddening.

So – short of expecting the publisher to fix the files or Sony to add a filename-based list instead, I'm looking for a way to fix the PDF metadata. I can view the metadata with Adobe Reader, but it doesn't permit modification of the properties. Leading to:

Question: Is there a tool – free, or cheap – and either for PC or Mac, that can modify the properties / metadata of a DRM-free PDF document? I want to correct "Title" and "Author" fields, specifically.