I got a fisheye lens for my Holga 120 CFN camera. I stuffed some 120mm film in there, attached the lens per directions, and proceeded to shoot some photos.
I think this lens is a fun gadget to noodle around with. I always have been fascinated by the fisheye effect, and was happy to get this lens for my Holga. I was actually surprised at how decent my results were.
See below here for more of my photos. The descriptions for each one is in the caption.
Do I recommend that all Holga users go out and grab their own fisheye lens? Nah, but if you want to give a try, be my guest. You can get them for some of your hard-earned scratch over at lomography.com.