Many folks have asked for an opportunity to contribute to DD's writing work without buying an ebook product. We're in the process of installing a dedicated app to make this possible.
But in the meantime the simplest way to handle it is to create a product in the store. The price we've chosen is about the same as a good cup of coffee in Dublin (the product pic comes from The Bald Barista in Aungier Street). Put however many of them in your cart as will suit your preference.
And DD says, "THANK YOU in advance for the thought. You folks are the best." :)
(PS: when you've been through the checkout process, the system will send you a link to a little thank-you card... and DD will most likely drop you a note after the fact as well.)