Kathi from Oak Hill Homestead just made her e book about making vinegar available for free if you sign up for her newsletter. I got my copy and have to say that it is a very good intro to making vinegar. She goes through the process and gives good tips and hints through the twelve pages of the book. I've made some different vinegar varieties over the past few years but I'd never thought of some of the ones that Kathi has created, such as pineapple vinegar. That sounds like it would be pretty awesome.
Here's a link to one of Kathi's blog posts about making vinegar: Homemade Vinegar