Many questions will be amenable to the FAQ approach. For a list that can be considered as our first FAQ attempt which will point, for now, to work on the subject related to the question (either a post or Wikipedia or Gardner's Beacon).
See interim Gardner FAQ.
Note: "Answering questions" post mentioned a collection of topology problems (Pearl, Elliott (2007) Open Problems in Topology II Elsevier) as an example of our usual state of having more questions than answers. This link is to the Second Edition (1,613 problems).