I'd check out Barton Associates locum tenens - they focus on travel NP jobs, and are very good. They also work with the facility to handle any credentialing related issues on your behalf, so it's pretty painless.
I would also look into locum tenens nurse practitioner jobs through Barton Associates (http://www.bartonassociates.com). I've had good luck and they have a rapidly growing NP locum tenens department... Just my 2 cents...