PrimoPDF (free) is a printer driver that creates PDF files from your documents, rather than printing them to paper. After install, whenever you choose the print option from an application, PrimoPDF will be listed along with your physical printers, print to file, etc. It's extremely easy to use and produces excellent PDFs--without the watermarks that some programs add.
Probably the best feature of PrimoPDF is the selection of templates for optimizing PDF output. Simply choose your output destination: the screen, a printer, ebook, or prepress (print with full image resolution) and PrimoPDF will create the PDF with that in mind. You may also enter tag information, referred to as document properties, such as the title, author, subject, and whatever keywords you specify.
PrimoPDF also allows you to secure your document. Unlike in older versions, you don't select the level of encryption; everything is 128-bit. You can specify a password to open the document, as well as a separate password to administer the document, i.e., change the password. You may specifically allow copying of text from a protected document, but this option is disabled by default.
Unusually, the setup routine offers to install a reminder app from the ASPCA--a nice break from the usual Google or Ask toolbars. PrimoPDF is a leader for the company's Nitro PDF Professional, so you'll see ads in the PrimoPDF dialog. If you want something effective without ads, try BioPDF PDF Writer or Nitro PDF Reader.