You know the situation, when you report a bug in the kernel and then ideally you're asked to test a patch? This means you have to compile your own kernel to test it and that means a lot of time: setting up a build environment, compiling, testing, compiling again, .... Depending on your skill and machine this may take a lot of effort.
It seems to be this could be so much easier and faster. The quick&dirty fix: e.g. the Ubuntu kernel ppa could provide a package with the already compiled sources so that you only have to compile that part which changed - if that would even work. The better fix: you could request a compiled image with a certain patch applied. That would not take too many resources - after all the compiled tree would already be there. And it would make things enourmously easier for debugging. It would not need to be available to the general public, but an "access key" could be distributed to someone who reported a bug in the bugzilla once a patch is ready for testing.
And what would help even more, would be if a git bisect could be done in the same way. If you had a powerful compilation server and you bisect via a web interface, download a kernel image, test it, and then tell the interface if the error occurred or not. Of course that would take much more power. But that's exactly why it would be great to have.
And overall, all this would improve the kernel debugging a lot and reduce the effort for developers and users with debugging.