Currently credit memos don't store if their transaction was done online or offline. This can make it hard to tell what's happened to an order if there are multiple credit memo's applied to it. I suggest adding a column to sales_flat_creditmemo called online_refund that's a tinyint and is set to 1 if the refund is done online. This could then be added to the Credit Memo's main grid and when viewing an order and would enable quick filtering to see just the online or offline refunds.
This has great benefits from the merchant standpoint because you can then easily reconcile refunds made through Paypal (or whoever your gateway is) and refunds made by cash or whatever other method.
I would be willing to submit a pull request for the feature if it's something Magento is interested in.