Assuming you mean a US bank that you can have access to while overseas, I personally use State Department Federal Credit Union (although it has membership requirements, anyone can join by choosing the American Consumer Council option on the online membership application); I like it because it's geared towards people who travel overseas, and is one of the very few US banks to offer both a regular credit card and a secured credit card (no credit check, credit limit based upon how much you have in the bank) that have a true chip & pin.
The chip & pin is becoming an overseas standard, and most US card issuers use a chip & signature, which is not quite the same thing. Also, all of their cards (including the secured card) have no foreign transaction fees which can save you a bunch when using it wherever you are serving.
One piece of advice is to have someone that will be staying back here in the states (family, REALLY trusted friend) have access to your account so that you can have money deposited if needed. Obviously not everyone is able to do this...
If you are talking about bank recommendations to use overseas for your living allowance, once you get overseas you will establish a bank account locally, and Peace Corps staff in country will tell you which banks are an option. The PCVs who are currently serving will be your best resource for choosing among them (assuming you have a choice).
Hope that helps!