I downloaded and installed Dropbox but I think its use is for something else (transferring files via WiFi) than my request (reading PDFs).
I already have loads of PDF files on my iPod (which I've dragged from my Mac's Finder over to the iPod section in iTunes and want to read there. They all show up within "iBooks". So all I need is a decent reading app which will allow me to continue to the next page without having to rezoom/reposition the text every time as with iBooks.
You also suggested using another PDF app. I've downloaded several, but I can't figure out how to access the PDFs I already have with them and they also seem to be geared towards buying/downloading ebooks from online. I have no need for that. Just a plain and simple PDF reader