Absolutely ask for compensation. Insist on it. If the work didn't have worth, they'd not want it in the first place. And by giving it away for nothing, you make it much tougher for our fellow photographers who do this for a living (maybe you yourself?)
Perhaps payment could be in kind for goods or services, as @MattKing suggested; but this should be spelled out in writing so that each knows the value of what the other is trading in the transaction.
Grant usage rights; DO NOT TRANSFER COPYRIGHT---read the fine print.