Wow! You're really dedicated to the fish-eye perspective. It's really interesting to see what you can do with one of these very special lenses.
I use a 15mm diagonal fish-eye quite extensively, but mainly as an ultra-wide angle lens. "Diagonal fish-eye" means that it only covers 180-degrees on the diagonal and will not produce a round image, as in most of yours.
I like to use my 15mm to move in really close, take a wide image and then de-fish it with my DxO Optics Pro Raw conversion software. Here's a de-fished selfie:
502 Selfie by
dcstep, on Flickr
Note the starburst at the top of the image. This is something that my particular Canon 15mm does particularly well at small apertures.
Ultra-wide and fish-eye lenses open up a whole new perspective for many photographers. Trying an image de-fished often leads to interesting results.