I am a Firefighter/EMT. Here are links to some great software available on your phone or pda.
For all non-emergency personel, it is good to have just in case you see an over turned truck or train car. You can help 911 dispatchers give the responders a heads up on what they are dealing with.
2008 ERG (Emergency Response Guide)
http://www.phmsa.dot.gov/hazmat/library/erg#page6
W.I.S.E.R (Wireless Information System for Emergency Responders)
http://wiser.nlm.nih.gov/