Off the top of my head I'm thinking self help stuff like self hypnosis and subliminal CDs for building self confidence, overcoming depression etc.
Here are some ideas:
"self Help" affiliate program - Google Search
The other one you may have good luck with is a health supplements/vitamin affiliate program and only feature St. Johns Wort and other products that help with anxiety and depression.
I can't personally vouch for any of these programs but have heard affiliates talk (mostly positive) in the past, about Native Remedies & eVitamins - they both have mood support products.
I'll try to think of some more. If I was going to go off and be an affiliate, which I don't have time to do, I would target something Mental Health related. Not for the money but more because I have background, interest and like helping people.