There are many resource sites for the DCU, for the Batman titles, for the characters, but I have yet to find a site with character details which really rigorously annotates where the information and canon details come from, sort of like this -- unfortunately no longer updated -- Batman timeline site which lists the events and the comics.
I think that would be very useful for any biography and character site, because there exist so many versions of the most important past events: retellings of origin stories, flashbacks, slight variations etc. that it is hard to keep track of what's constant, what's changed, what details have been modernized over time, and what conflicting versions there are.
The Unofficial Guide to the DC Universe does a great job with the chronologies and the indexes even for minor characters, and though it's being still added to and has some gaps, it's already a comprehensive resource to find out in which issues some character appears, for example, or for finding publishing dates or creator credits for an issue, yet it is not much help to connect character facts to specific issues. And most character biographies on the web sort of skip over citing the specific issues their biographic details are based upon.
I mean, for TS there were even pages keeping track of the number of times white socks were a visible part of Jim's outfit, surely there have to be similarly detail-obsessed Nightwing pages listing things like all instances Dick refers to his parents, mentions the circus, etc.