Actors Access (which is affiliated with Breakdown Services): www.actorsaccess.com
Sign up, post your picture, enter all your resume and contact info and you're good to go. They have casting updates throughout the day, and you can also sign up for email notification if something right for you comes in. Most of their notices are LA-based, but there's a lot of NY stuff too.
The only "catch" is, if you submit yourself for something electronically through them, you get charged $2 per submission. But then, a lot of the notices they get are for things you won't find duplicated in Playbill or BackStage, so I find it's worth it.
