Just signed up and indexed a few pages. After seeing you're caching pages I started thinking about privacy/security issues. Your privacy policy isn't very reassuring. (DuckDuckGo does a great job at this: http://duckduckgo.com/privacy.html)

Having the client perform the task of indexing is great, but it also means I can index pages that only I am supposed to see. Which raises the question: are you going to do anything with the index and cached pages I've built up? If I index an interior facebook page, for example, will you ever expose the cached content to other users of historious?