I've been reading about epistolary novels, and was wondering what you thought about the concept. Is there an app or something similar that allows you to make fictional documents? And have you tried it at all? I've also heard that some people include traditional prose to spice it up, such as Stephen King's Carrie. How well does that fit in?
Check out Steve Kruger's Last Days of Summer. Excellent epistolary novel with all sorts of funky formats for the correspondence.
Dracula is a great example of this. It used different forms of communication from various people, and it even explains how they were put together. It adds to the atmosphere, because the initial letters/telegrams/... are from people with no idea of the danger, but the reader can see what's happening.
Dracula is definitely an inspiration. I read it once, and it fascinated me in how it constructed and told a story.