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Why not convert the PDF to HTML yet still have a download PDF button for clients if desired?  Heck there are lots of free tools to do this, but check the code.  Or you could just use an ALT tag which aren't just for images but for objects.  Not sure if PDF's with ALT tag give much link juice, and if I HAD to keep it as a PDF, I'd convert it to a compressed JPG file and use an ALT tag so that Google knows what the object is and keyterms.

use it for cross navigational purposes only (user experience) don't use it for SEO or you'll get penalized if you're passing page juice. Nofollow all of them by default if you need to interlink, better you don''t interlink them.

Thank you guys for your answers! I realize that other strategies are more effective and less 'gray', but I was just wondering if it could work in theory. I'm not planning on buying hunderds of broken typo domains, but I figured that a link from a direct competitor could be pretty valuable. But if 301's lose juice like Gareth said, one link might not be even worth it. @Takeshi; Thanks for suggesting Xenu, I'll check it out!

Hi Roel! I´ve spoken to people in many different countries about this and they all confirm that the Penguin update is spread everywhere. Google said this: _The change will go live for all languages at the same time. For context, the initial Panda change affected about 12% of queries to a significant degree; this algorithm affects about 3.1% of queries in English to a degree that a regular user might notice. The change affects roughly 3% of queries in languages such as German, Chinese, and Arabic, but the impact is higher in more heavily-spammed languages. For example, 5% of Polish queries change to a degree that a regular user might notice. _ More reading: http://insidesearch.blogspot.se/2012/04/another-step-to-reward-high-quality.html Hope this will help you!