A NAM (Navy-Marine Corps Achivement Medal)can be handed out in a discresionary manner by unit COs. I have seen them issued for the following:
Baking Cookies (the infamous "cookie NAM")
Not Fvcking up during a hi-viz inspection (to the officer responsible)
Not Fvckign up during a tour (normally, a NAM is an end of tour award for 1st tour LT's here)
Changing an engine and getting the aircraft back up in 5 hours (to the 3 AD's who kicked a$$)
Plus, many other meritiorious reasons. It's kind of the cover all for "worthy of more than a letter" situations.
FWIW, I do not have a NAM, but I did get a COM (Navy-Marine Corps Commendation Medal) for flying SAR & MEDEVAC during JTF Katrina. That probably was more like a JAM (Joint Achivement Medal) but the Commodore was having trouble getting the 82nd airborne's CO to sign off on it so he "upgraded" it to a COM.
For the confused, there is a precedence order and description of criteria here:
http://www.gruntsmilitary.com/navyrib.shtml