How do you make money on something nobody is using?
A technology that works but isn't deployed is not a technical problem you need to solve — it is a blockage you need to charge for removing. So the business you should build is dictated less by the technology than by what is holding it back. Find your entry's blocker chip, then read the matching play.
Method & honesty notes
Candidates were researched domain by domain against public sources, curated down to 100, then put through two independent audits: a readiness auditor whose only job was to kill entries that are not genuinely proven, and a business reviewer attacking the weak commercial plans. Entries that failed were rewritten or replaced.
The bar for inclusion is demonstrated function, not commercial success: a completed pilot, a certification, a plant that ran, a country where the thing is ordinary. That bar deliberately excludes fusion power, room-temperature superconductors and similar — technologies whose central claim has never been physically demonstrated. It also excludes anything already scaling in the mainstream, because that is not latent, just new.
"Not deployed" is a judgement about scale, not existence — most of these are used somewhere, by someone, which is exactly the evidence that they work. Stated blockers are the dominant reason, not the only one, and reasonable people will disagree about which one dominates. Nothing here is investment advice, and anything touching medicine, food safety, energy or finance is regulated for reasons worth understanding before you build.
A companion list: this site's sister project looks in the opposite direction — 100 obsolete technologies worth reviving, where the technology already proved itself, was abandoned anyway, and the opportunity is in bringing it back. Between them: things too early to have been used, and things used up and discarded too soon.