I am one of the many whose research depended on Dave's vast knowledge and, more importantly, willingness to help. In fact, Dave was the single most helpful and encouraging person I encountered while in graduate school--I might still be there spinning wheels without him. He not only cared about my research, he cared about me as a person. He quite literally saved my defense seminar when my computer blue screened and I was too stressed to fix it. He went far out of his way to support me on that day (and many others), and, in his gently way, he helped me deal with my father's slow decline and eventual passing.
I hope that we can all follow Dave's example, and not only store our vast personal wealths of knowledge and information, but share them, amicably, not for our own personal benefit, but for everyone's.