X-23 is credited as having been created by Craig Kyle from NYX v1 issue 03 until New X-Men: Academy X issue 43. As of New X-Men: Academy X issue 44, he no longer received an insert that marked her as his creation. The common misconception is it was both Yost and Kyle that created her. During an interview it was revealed that Yost had added the foot claws to X-23's design. Yost also co-wrote the origin miniseries and X-Men Evolution episodes she premiered in as well the New X-Men Academy X and X-Force v3 comic run that they are both credited for.
Duh. This is X-23's Wikipedia page.
The Official Marvel Universe Wiki
Her entry over at Marvel.com's personal online wiki. The self-proclaimed definitive Marvel character wiki.
A wikia for X-23 and her alterniverse counterparts.
Movie Info Collection Blog
A very well written character brief about X-23.
KinnyPride: X-23 Timeline with Ages -Offline for updates and corrections.-
This timeline is continually updated as new information becomes available or I finish going through back issues to correct the older information.
KinnyPride: X-23's Reading Order
Or at least it will be if I ever get off my lazy butt to finish building it.
KinnyPride: Common Misconceptions About X-23
Details about X-23 that can be missed if not observant.
KinneyPride: X-23: A Guide to Triggerscent
An explanation of Triggerscent. How it has been programmed into her, what it does, and a myriad of examples of how it's been implemented, adapted, or used on her in comics and stories.
KinnyPride: RSS Feeds and You.
A quick how to, and suggestions on aggregating the quickest news for oneself.
X-23 Psychology References:
Marvel.com: Psych Ward: X-23
Marvel's resident Psychoanalyst Tim Stevens takes his crack at X-23. (Out dated due to recent physical reinforcments and other factors.)