What kind of problems to you mean specifically? By "one decision problem of one person" do you mean problems that may arise in day to day life, or is the scope allowed to be wider than that?
I'm thinking things like deciding whether or not to take a job, what major to choose in college, whether to continue or end a relationship, choosing which of several business opportunities to pursue, etc. What do you have in mind by a wider scope? Can you give some examples?
It's one thing to read about a subject, but one gains a deeper understanding by seeing it applied to real problems, and an even deeper understanding by applying it yourself. This applies in particular to the closely related subjects of rationality, cognitive biases, and decision theory. With this in mind, I'd like to propose that we create one or more discussion topics each devoted to discussing and analyzing one decision problem of one person, and see how all this theory we've been discussing can help. The person could be either a Less Wrong member or just an acquaintance of one of us.
I'll commit to actively participating myself. Does anyone want to put forth a problem to discuss?