While we have all of us here together to crunch on problems, let's shoot higher than trying to think of solutions and then finding problems that match the solution. What things are unsolved questions? Is it reasonable to assume those questions have concrete, absolute answers?
The catch is that these problems cannot be inherently fuzzy problems. "How do I become less wrong?" is not a problem that can be clearly defined. As such, it does not have a concrete, absolute answer. Does Rationality have a set of problems that can be clearly defined? If not, how do we work toward getting our problems clearly defined?
See also: Open problems at LW:Wiki