I've built something similar for my crawler at biztoc.com — It does OpenGraph extraction, finding the body, summarizing it, tag & entity extraction, sentiment analysis, Oembed, stock symbol detection, screenshot & favicon, etc.
Great job on this! It looks fantastic and I think you'll do well. I like how you moved to token use for logins. Passwords are dumb.
I thought about these types of features for Mitta.us (which is NOT done, but operational), but it was too much work. Glad I put it off, because you did a much better job.