What non-fiction topics do publishers and agents hunger for?
First, I'll apologise for using the word 'hot' in the header but I wanted to rhyme with 'what'. And now I'll get to the answer ... which should have appeared a few weeks ago, but I overlooked the question in my list! Apologies to the person who sent it in.
The non-fiction topics that publishers hunger for are often the ones agents can't get their hands on: specifically, autobiographies of sportsmen (and I used the 'men' bit on purpose). Sports agents tend to look after the book deals for their talent; it's rare that a cricketer or AFL footballer looks for a literary agent. The other non-fiction books that sell very well are cookbooks, but that can depend on whether or not the chef has a TV show, or whether there's a well-known brand attached to the book.
Each agent has their own interests and specialties with both non-fiction and fiction, but generally speaking memoir is a dominant genre (and covers a lot of ground - it could be a memoir about being a call girl or running a cattle station), as well as true crime, military history, medical and the odd motivational story. Science is also sought after, but it depends how it's written - if it's too academic, the audience will necessarily be small. Travel writing is a bit on the wane, unless it's done by Michael Palin. Business books can be tricky - again, a well-known face helps.
I suppose a basic rule for non-fiction is that if the author is famous (for doing something other than writing), publishers will want to talk to them. If the author isn't famous, then the topic needs to be something that would grab a journalist's attention, because the book will need publicity in order to clamber above the other 999 books published that month.