This is one of the most unusual coins I have seen. I don't think the stackers will take it seriously, but it's an interesting twist. From the website: "Each individual product appears as a flat, singular coin, but is in reality a series of four concentric circles. Each of the four circles consists of oz of .9999 pure gold, and bears a face value of $25. The coin can be twisted into a piece of artwork that resembles an armillary sphere, or even separated using CombiBar technology into four separate coins." http://www.jmbullion.com/1-oz-valcambi-gold-armillary-sphere/
That is awesome. I would love to see one like that in Silver. Not for stacking value, just for coolness factor.