I built Canada's first (and one of the world's first) crowdfunding websites that attracted over 115,000 members without any paid customer acquisition and distributed over $3m to charities so I can certainly attest to the fact that sites that focus on creating positive outcomes are attractive to many people.

There are however, several challenges to executing your idea well. Some of them are:

Can it be truly helpful? Just like this site (Clarity), the challenge is for the answers to be genuinely helpful to the person in need. Giving bad advice or allowing negative commentary could be incredibly damaging to the psyche and overall well-being of your community. The potential cost associated with vetting the people able to provide help could be a significant barrier.

Anonymity: I have built several applications that allow for anonymous messaging and have learned that people are reluctant to trust the promise of anonymity, so there are product challenges to getting the people to post sensitive information. These can be overcome but they are not without significant challenges.

Peer Support is challenging: Providing users an open-ended mechanism who are going through something the ability to offer suggestions to others *sounds* like a good idea, but again, can be very damaging. Extensive moderation would likely be required.

The best (i.e. potentially most helpful) service I've seen so far is a text-messaging based service for teens in crisis. Here's an article to it: http://www.ctvnews.ca/health/health-headlines/crisis-hotline-operators-reaching-out-to-teens-1-text-at-a-time-1.1217225

I think if you're going to build something, it should be mobile and figure out a way to sustain the business or service that supports paid staff or at the very least trained and vetted staff to be primarily responsible for helping individuals in need.

Happy to talk this through with you if you are (or when you become) serious about pursuing this idea.