This is a very interesting thread. I'll have to look through my recent shots, but I don't think I have any monochromatic ones. However, I do have at least one monochromatic image from years ago.
Kodachrome 64, Canon A-1, Sigma 600mm f/8 mirror:
Here's another that's almost monochromatic. Also a Kodachrome 64 slide but a crop of a small portion of it. The Camera was a Canon AE-1 with a 50mm f/1.8 lens.
By the way, I duped the slides using a NEX 7 and a rig I cobbled together, which includes a Nikon 55mm f/2.8 Micro-Nikkor at its core.
I'll look to see if I have more.