Some of the most challenging yet most rewarding photos I have taken are those of my own eyes. The challenge was shooting these blind while I hold the camera up to my eyes and use a lot of trial and error to try and get both something sharp while keeping my eye in the frame. After close to a hundred attempts I did end up with a few sharp and detailed images.
Nikon D90 1/30 f/7.1 ISO-100 at 105mm
Nikon D90 1/30 f/7.1 ISO-100 at 105mm
Nikon D90 1/30 f/7.1 ISO-100 at 105mm