Jeez, people. Do you not understand that interest is haram (forbidden) in Islam? That is the whole point of establishing such a bank.
Offering interest to a Muslim is like offering a ham sandwich to him.
Indeed, that's why no one in this thread has wanted to add an interest rate.
Though, darkmule is right. It is good for people to note, it isn't compliant with Sharia banking practices to "take money for money".
However, in my experience, it is normal to offer collateral, goods, and/or services. It's always good for the bank to feel secure in loaning to a person/company; but, it all depends on what the borrower can offer.
Also, gratuities/tips are usually allowed as well. Tipping someone for good service is never unappreciated by a service provider. But, a tip can not be used in order to obtain money.