MoDaCo.SWITCH: Switch between Sense and Google Edition on the HTC One
MoDaCo.SWITCH is an upcoming ROM for the HTC One that will allow you to boot into either Sense or the Google Edition ROM, while - most importantly - keeping all your data in-sync. More info, as well as a video demo, can be found here:
MoDaCo.SWITCH for the HTC One - demo (via paulatmodaco)
I think this is actually kind-of amazing - I always wanted this one my One X, when I felt I had to choose between the performance of AOSP or the camera/battery life of Sense. Of course, I like Sense 5 quite a bit more than Sense 4, so I haven't ROMed (or even rooted) my HTC One - but I might do so at some point just to try out this ROM.
The developer says he's also working on a "best of both worlds" ROM, where you can choose which specific pieces of functionality you want from Sense and AOSP, but this one will be available first.