ReadWriteTweet: a Twitter directory of YA authors, characters, and reviewers. (Literary agents too.) You can add or update a tweeter or follow me @readwritetweet.
Have fun.

First, the rules:

Authors must be published or have a book sold to a publishing house. While I’m all for writers who have yet to hit the market, creating a comprehensive directory of them would be overwhelming.

Please note: this directory defines YA as having a protagonist of at least fourteen years.

Agents must have some sort of web presence (even if only interviews). Makes validation so much easier.

Everyone else should provide a little extra information, such as a site link or who-I-am statement.

For updates give your name and twitter id, and skip to the final text area to list changes.

Updates/new listings will be added within a week of submission. If they don’t appear, or if you have questions, DM @readwritetweet.