OK, I took a picture in the same style as the diving board photo. I also used to own a Barney converter. I started a list of some of the others based on what I've seen over the years.
Name: Mirai
Pros: fits in a Duo and Turbo Express, still available from Telegames.uk, one of the cheaper converters (but still expensive)
Cons: tarnishes easily and needs cleaning, PCI slot can rough up the bottom of hucards
History: made by Telegames, sold at TZD in the early 2000's (anyone remember the price? $99? $75?)
Photo: vestcoat
Name: WH-301, A.K.A. the "Barney Converter" (label says "TV Game Converter")
Pros: one of the cheaper converters
Cons: Generally considered to be one of the less reliable converters. Physically incompatible with the Turbo Duo - power switch runs into the plastic housing. Some users have solved this by chopping a hole in the lower-left corner of the case. Many units are missing the top plastic cover.
History: Came packaged in a small box. Called the "Barney converter" because it's purple. Brown models have also been reported.
Name: Kisado
Pros: considered to be the most reliable converter
Cons: expensive
History: Made from a rare sewing machine socket. (IIRC, this was fan-made by Turbolist members, can anyone confirm?)
Name: PC-505
Pros: black
Cons: perhaps the rarest converter. Many units missing top cover
History:
discussed herePhoto: hoobs88
Name: Chopsado
Pros: the only affordable converter, reliable
Cons: has to be carefully secured to hucards, fragile
History: designed by Chop5