As I was working on the Tetris list I realized that the little known NP Carts have not been discussed much.  A quick Google search and there are a handful of good solid reference(see below) to the Nintendo Power Kiosk and how they were intended to be the "new way" to distribute games without real carts.  Sadly it never took off and so we are left with stuck in time game carts that are loaded with unknown games until you power up with your retro GB.

Summary:

There were 129 known titles (data from Nintendo Japan) that were able to load via a kiosk mostly located at Lawson stores through out Japan.

Game List:

According to mariowiki only 14 games were for the GB, while others (nindb.net) list 28. 

There are two Game Boy CIB, only one was shipped with a pre-written game, a version of Super Mario Land 3: Wario Land.

SF Kiosk service started September 30, 1997 and discontinued August 31, 2001.

Game Boy Kiosk started March 1, 2000 and discontinued August 31, 2001.

However there was a continued a mail in service until September 1, 2007

image from https://static.giantbomb.com/uploads/original/9/97089/2852997-tumblr_ku0r0srl2h1qa5kxw.jpg

Resources:

Metro's Data:  https://www.giantbomb.com/nintendo-power/3015-8760/

Wikipedia Data:  https://en.wikipedia.org/wiki/Nintendo_Power_(cartridge)

Nitro2K01 Data:  https://blog.gg8.se/wordpress/2013/02/25/gameboy-project-week-8-the-white-nintendo-power-official-flash-cartridge-a-tale-of-reverse-engineering-sweat-and-tears/

Mario Wikipedia Data:  https://www.mariowiki.com/Nintendo_Power_(cartridge)

Nintendo Power Super Mario Land 3: Wario Land                                                                                                         Nintendo Power Blank Cart