WIPO has a very useful list on its site of patent landscape reports.
These are analyses of trends and patterns by country, company and so on of particular sectors. They are arranged in the broad categories Public Health/ Life Sciences, Climate Change/ Energy, and Food and Agriculture.
Many are available to see as free PDF links, but a few at least only lead to a free abstract and the report must be purchased. I would encourage anyone who has published such a report, or at least knows of one, to mention it to WIPO, as I am sure that there are a lot more than the 50 or so listed. I am not sure if comparable academic papers qualify as well -- personally I don't see why not. And surely there are other sectors such as engineering to cover ?
I myself suggested to them a 2011 report compiled for the UK IPO on medical devices and telehealth by CambridgeIP. I found it in a little-known but very useful (and free) Zanran database, which looks for data such as pie graphs and bar charts in Web documents. It is best used when there are a couple of well-defined terms as opposed to an area where there are lots of synonyms.
The site is a great favourite of mine for trying to reduce the number of hits otherwise found on Google to a managable (and largely relevant) amount, and it's easy to scan the results by letting the cursor move down the images of the documents.