Remember all those adverts in black and white in MBUK in the early nineties for ill thought out technology that you would order from someone's house?
My particular favourite, the nard gard – a bit of foam in a pouch that you straped to your (quill)stem to protect your nads if you slid along the top tube.
close second, Wedge packs that you put in the join of the seat and top tube to pad your shoulder for when you had to shoulder the bike and run in an XC race (not a bad idea, but when doubled into a bag full of tools it became a little pointless).
Also Power grips -diagonal strips that went accross your platforms to make them kind of toe clips but without the toe bit.