We just need a site for posting null result reports.

With really good keyword, search functionality.

Much less formal requirements than regular papers, make it easy. But with some common sense guidelines.

And public upvotes, and commenting, so contributors get some feedback love, and failures can attract potential helpful turnaround ideas.

And of course, annual rewards. For humor & not so serious (because, why so serious?) street cred, but with the serous mission of raising consciousness about how negative results are not some narrow bit of information, but that attempts and results, bad or not, are rich sources of new ideas.