Switch Lab
Mechanical keyboard people are a particular breed, and I mean that as a compliment. They will argue for hours about linear versus tactile switches and spend real money on spring weights, yet most of that decision happens blind. Switch Lab's idea to let you hear and type on switches before you buy targets a genuine pain point in a community that cares about feel more than specs.
The try-before-you-buy model has worked for mattresses and glasses, and keyboards feel like a natural fit. What I'd want to know is how deep the catalog goes and whether they can capture the subtle differences in sound and actuation accurately enough to matter. If they pull that off, this could become a default stop for anyone planning a custom build. The risk is that it stays a novelty, but the audience is obsessive enough to reward a tool that respects their fussiness.
