Debenu PDF Tools Pro is a collection of tools which can help you manipulate PDF files in many useful ways. Normally $59, it's currently available for free - but we don't know how long this offer will last, so don't spend long thinking about it.
Once installed, right-clicking a PDF file and selecting "Debenu PDF Tools Pro" will display a menu listing its options. And you should start by entering the registration key provided. Just choose Application Info > Register ..., and enter your name and the registration key included in the downloaded archive (see debenu_pdf_tools_pro_license_key.txt). Then right-click a PDF file again, and browse the various tools.
A "Convert" menu allows you to convert PDF files to text or images. You can also select multiple images and convert them into a single, or multiple PDFs.
The "Extract" menu can extract text and images from a PDF file. You might use this to grab the embedded images within a PDF, say.
The "Security" menu allows you to add or remove a PDF "Open" password, or apply a digital signature to the file.
There's a simple PDF viewer, a document properties tool, and an option to extract PDF form data.
There isn't always a lot of depth to these functions. If you're converting a document to images, say, you don't get to choose the image file format, the base file name, or anything else: just specify a file folder, lots of JPEGs are dumped there, and you're left to organise them yourself.
Debenu PDF Tools Pro does still provide a great deal of power, though, while also being very well presented and generally very easy to use.