If you're looking for a low rate emergency type card, their plain jane Mastercard is great. If you're looking for cash back, their Cash Rewards card is good also. It gives you 1% back on annual spending up to $10,000, and 1.5% thereafter.
NFCU is pretty lenient. Scores in the 650s should do it, but I think 660 or higher is optimal.
I just applied for their cashRewards Visa and the Platinum MC this week, and was approved for both. My EQ is also about 650-ish. They gave me $7,500 on the Visa, and $6,000 on the MC. And I only had the savings/checking account open for one day when I applied for the cc's.
You can go to http://www.navyfederal.org/credit_cards/creditcards.html to compare their cards and decide which one fits your needs best. Do you want something with no annual fee? Do you travel a lot and want rewards that will give you discounted/free airline tickets? Do you like points being awarded that you use to get gift cards, or would you rather receive cash back as your reward? Do you want to take advantage of free concierge services? Lots of choices!
Good luck, and let us know the results if you decide to apply!