Wow, this is fantastic! The more resources we have like this, the better, I think. I really like how you differentiate between the more important books and the side stories, and specifically point out where to jump on.
I think emphasizing chronological order of different parts of stories over a reading order of entire works might be a bit confusing; I agree that a suggested reading order, or something like VotI did where it listed the "core work" where most of it fell chronologically and then gave little parenthetical notations for different parts of the books, might be a good addition. But still, I just spent like a half an hour playing with all the lists... great fun.
The one thing your site doesn't do is give a good indication of how the series connect to each other... but that's what the timeline I started and 8of5 expanded is for anyway.