Thanks :)

For ranking, instead of textual relevance (which will be hard to achieve :/) and # of quotes (it can be easily hacked/spammed or new announced books will have a huge weight on the ranking), I suggest you to check timelines: if a book is quoted once/twice/... a month regularly, I'm pretty sure it worths reading it

I'll love to read about the architecture behind the site... yep, technically curious :)