Jeremy, check out a short article we did on this a little while back, it has some recommendations: http://www.firefighternation.com/article/training-0/smartphone-apps...
Wiser, for hazmat stuff. the complete NIOSH and ERG book combined
Best iPhone app I have is "911 Toolkit." Has a lot of useful stuff.
Not sure what you're trying to get out of the app, but if you're looking for fire service and EMS news,Daily Dispatch has a great app that you can download for any mobile device.