2 sides to this, 1. Protecting brand and 2. Just want more results for a keyword.
With regards protecting brand, using other sites worked best for me.
Putting YouTube content on mydomain.tv, putting company info on a .info, creating my own affiliate sites with brand name in the URL. A few of these and you can control the first page for your brand quite easily.
Also with language Googles assigning a folder to a language in WMT and building links from those language sites into it seems to give me an easy 1-2 with /county/ first and plain dot com second.
For getting more results in on a specific keyword, yes pdfs or other media types (either youtube videos or host my own and make a video sitemap). If you can get into Google News (depends what kind of site you have) that's good. Plus getting a few Twitter accounts to tweet about the keyword can get you to show up.
Both ideas kind of overlap but I find the domains provides more stable control where as the other media varies wildy by search.