The United States National Library of Medicine has an excellent service called DocMorph where you can convert 50+ different document formats to PDF. You have to register (which is free), and then you find a file on your computer, and it converts it. It does a good job of optimizing the output.
I tried it with a simple Word document (logo in header and text in body). The original document was 62kb, and the converted PDF was 29kb. I tried it with a 136kb GIF, and the converted PDF was 165kb. Lastly, I tried it on the PCIN Registry Tips document. The Word document was 330kb, and the converted PDF was 257kb. I had used Acrobat to create a PDF already, but it was over 400kb, so I’ve since replaced it with the smaller one.
There is also software called MyMorph which you can download. I did not try this as I was only testing the web-based options.
It’s definitely worth checking out.