Without a doubt, this burn in test cartridge seems to be the most common. What it actually does is allow you to test the the various SNES accessories; like the controllers, Super Scope, and the mouse. Depending on what accessory is in the first controller port, a different screen will appear to guide you through the test process for that specific item.
I know Nicola mentioned them yesterday, but I though I would look at them a little more in depth. I know a lot of people have put extensive effort into finding these old Nintendo Authorized Repair Centers and purchasing their inventory, and that no doubt has a lot to do with an influx of test cartridges.
Nintendo also put an end to their Service Centers (although from what I understand a select few retained their status) in what I would consider the recent past, sometime after 2001 I believe. That’s only a mere seven years ago, so we’re probably reaching the point where where former store owners are realizing what they have in there possession as well.
Either way, I find it pretty interesting that are three available right now.