Create an automated way of creating a customer refund, including the creation of the vendor invoice for the refund that can then be paid by check or EFT. For reference, this capability is already very nice in Dynamics GP.

When a customer has a payment with a remaining balance, there should be an option to "create refund" or something of the sort. That would then fire a series of functions to
1) enter the refund on the customer record,
2) post transaction to the GL (debit accts receivable, credit a 'refunds owed' account),
3) create a vendor record for the customer if one doesn't already exist,
4) create and give option to review/post the vendor invoice,
5) post vendor transaction to GL (debit 'refunds owed', credit accounts payable),
6) give option to create a payment right then or allow user to wait and include payment with others.