I thought the intent of this project was to shoot something yellow, not to play games in PS or other editing programs with post-processing? When I saw the first couple of these black-and-whites-with-a-shot-of-color I thought, "gee, how neat!" but now it is getting a bit repetitious and tiresome..... But this trend, too, will pass...
I'll admit, I'm pretty much of a purist and a photojournalist at heart, preferring to shoot my photographs "straight" and present them with minimal post-processing, showing the world as it is rather than tricked-out with excessive post-processing. When someone gets into extreme manipulation of an image in post-processing, it (IMHO) no longer is a photograph, it has become something else, a different art form. Not to say that this is good or bad, it's just that it is different from photography. I have seen some wonderful examples of digital art or digital art photography, but to me this is not the same as photography per se.
I love the yellow bus shot and I love Gekko's shot of the yellow socks sharply contrasted against the blue sky.
I have an idea for my "yellow" shot but just haven't gotten out there yet to do anything with it.