Sooo Riddle Me This...

So My brother is a professional book publisher and distributor (he owns his own company). He wants me to write a book on training and basically do a series. So one book on Stallions, one book on breaking, etc. etc. So I'd like to hear feedback on what type of books you would like to see out there. I know a majority of books on horses are pretty darn generic and they don't teach a lot, but the basics. So I'm taking ideas!!!! Let's hear 'em!!!!!!!!!!!