This should be easier than the zinc/iron coins challenge. Try and put together a complete type set of all the world coins minted by the USA for other countries. In an old copy of the Blackbook Price Guide To World Coins (1998) there is a list of them from the first in 1876 until 12/31/1980. I don't know if US mints have continued this practice since then but the source is the U.S. Dept. of the Treasury so you can probably get a copy of the list by Googling it. The list gives you all the coins by country, date, type and mintage. This should be lots of fun and I think you will be surprised at how many there are!
The hawaii stuff going to be pricey. I have Phillipino WW2 coins. If you count everything like Guam theres a lot. Good luck.
Yes, if I remember correctly, the NGC Registry used to allow both NGC and PCGS coins, though from their corporate viewpoint I can see why they'd change it to become exclusively NGC-only. PCGS' Registry has always been PCGS-only. Someone should create an independent registry that includes both of the "Big Two". And maybe the second-tier ANACS and ICG, as well, with some weighting. But I think you could draw the line at those four, since I believe that's what eBay does now. Anybody else could be considered "Third World". But then there's the sticky subject of stickers, like CAC for US coins, and WINGS on World coins. But the independent Certified Coin Registry could ignore the stickers for simplicity's sake, if they made algorithms too tricky.
I think it would be a very worthy endeavor for them, since an unbiased organization with some gravitas and clout really should be behind such a combined registry. I hope they do it.
