just starting in travel nursing business

i am working with a small healthcare staffing agency that has been successful in the perdiem market. we are now setting our sights on the travel nurse business. we ofcourse, will continue with perdiem but see great growth in going with contract nursing both local and afar. what i wanted to know is: besides med/surg nursing, what other specialty is in great desire by the hospitals and what are the top paying specialties in travel nursing
any other input towards getting into the travel nurse business will be greatly appreciated.
sandals