I highly doubt there will be any free CCRN practice exams online, but you may want to check with your hospital's human resources/continuing education heads and see what they have. I know at my old hospitals, the head of critical care education had acccess to several resources that we couldn't get. And if it's not exams, then it'll be protocols for situations (IABP, CVVHD, Vents ...) that you'll use in everyday practice. Here is an amazon site with some pretty cheap exam books ... I know they can be pretty expensive.
http://search.barnesandnoble.com/Oop...nInquiry%2Easp
Good luck on the exam ... it's a doosy!