If I'm going to fly an airplane that's new to me, I'll pull the AFM out sometime before the flight, even if it's a type I've flown before. Why? So I can look at the supplements to see what sort of gizmos may be installed on THIS airplane that weren't on the one's I'd already flown, and what they might do to performance or limitations.
If I've never flown the type before, I get a copy or a POH long before I take the first lesson in it, and I dig out the emergency procedures, the airspeeds for normal ops, and basically read the whole thing through.
If there's another required document (G1000 pilot guide for example), I'll read it if I haven't read it before.
In flight, the manual would come out any time I had a question about the airplane. In the last Flying Wild Alaska where the 1900 had the bad gear microswitch so that the gear indicated unsafe/in-transit, you saw the crew handle that situation pretty well - someone flew the airplane, there were no memory items, no QRH items, and they went and dug out the manual for any abnormal checklists related to this event.
Oh, just thought of a real-life example. While flying along, I saw the oil pressure start to drop a bit without a corresponding rise in temperature. I pulled out the manual, found the emergency checklist, then went to the systems description and was informed that if the engine temperature wasn't rising and the oil pressure was not in the red I didn't have a "land right now" situation. So I watched both like a hawk (this was at night) and continued the flight. When I landed, I found some oil in the belly and that the airplane had lost 2 of 12 quarts during the flight. Turns out a pipe in the low pressure part of the turbocharger oil system had cracked and was leaking.
And I agree that there are relatively few things that need memory responses. Even in bigger more complex airplanes in revenue service, the lists I've seen have one or two immediate memory items, then it's "get out the QRH". They all relate to things that will kill you quickly, like fires, powerplant failures, or depressurizations.
Jet jockies, care to comment on how many items are actual memory items in your checklists?