I have used NetBank previously and have been happy with the service. It has a feature whereby multiple read-only accounts can be permissioned to access accounts. This would allow all or some members of the Board (as decided by the Board) to have auditing rights of the bank account(s), but still restrict the ability to disburse funds to a select group of people.
Pending other suggestions, this is the solution I will adopt for Gentoo.
* Optional. Required to accept credit card payments/donations.
** The NFP entity must be fully established before this task may be finalized.