One thing I've thought would be useful for a while is a platform to allow people with unknown diseases to get matched up with others with the same symptoms.

While CrowdMed can help with rare diseases it's less useful in cases where a disease has never been diagnosed before.

In recent years we've seen a number of diseases/conditions essentially identified by patients discovering others sufferers (often through online campaigns) and the commonalities / genetic testing helping identify the cause. But these have largely relied on serendipity.

It would be great to have an online platform to allow people with unknown conditions to find each other.

(this is especially true with long-tail psychological issues where diagnose is often still very weak)