PDFFill Tools is a useful collection of utilities for working with PDF files.
The suite allows you to scan pages directly to a PDF, for example. You can convert images or PostScript files to PDFs, and a bundled virtual printer driver creates PDFs from any printable document.
There are further tools to split and merge your files, encrypt and decrypt them, or customise them with watermarks (text and image). You're able to add headers and footers, rotate and crop your documents, edit their metadata, work with form fields, and more. The program can even be launched from buttons in Microsoft Office applications and Internet Explorer, in theory at least (when we tried it, our copy of Word crashed).
While this sounds great, there is a problem: the interface. Each of these tools is represented by a separate dialog box, with hardly any visual feedback at all. If you're adding an image watermark, say, you don't get to view the target file first; you can't point and click where you'd like your picture to be, and there's no way to preview how the finished pages will look. Instead you must choose your image, set its position in inches, and export the file before you get to find out.
Once you understand how everything works, though, this isn't a major issue. The individual tools have some useful options and settings, and generally work very well. And if you do need a more visual approach, a trial version of PDFFill's PDF Editor is included with the package. It has all the features of the tools, and more, and can be yours for a very reasonable $19.99.