How to export a clickable PDF from Balsamiq Mockups
Per the Balsamiq Mockups FAQ:
To create an interactive PDF, all you have to do is open all the mockups you’d like to package together, link them up if you want and "Export All to PDF…" from the File menu. A single PDF file will be created, with a mockup on each page and even interlinked pages!
You can put the mockups in the order you’d like them to appear in the PDF by dragging the tabs at the bottom of the screen.
About the tool
Balsamiq Mockups is software for creating rough, low-fidelity wireframes with a hand-drawn, yet consistent look. I’m a big fan of the “drawn” look for wireframes, as I think it goes a long way towards ensuring the client understands what they’re seeing is unfinished: it keeps the focus on the interaction rather than the visual appeal.