Weirdest Collection Themes You Have Ever Seen?

I have at least one dated coin from 1600-2017 at present. There are many gaps before 1600. Most coins are silver, some are copper (etc.), and a few are gold.

I have been working on and off on my collection of "gimmick" coins - just one with each class of gimmick (an example being the incuse design $5.00 and $2.50 US gold coins from 1908 to 1930).

Another collection I'm thinking about is getting coins from German principalities with the most complex-sounding names. A good example is Braunschweig-Wolfenbuttel -- the icing on the cake is the umlaut over the "u". Others I like are: Brunswick-Grubenhagen-Herzberg-Osterode and Ottingen-Ottingen.

That is too bad. I for one love going through all manner of foreign coins and figuring out what they are, checking the types off in my world coin catalog, and putting them all in labeled 2x2's in folders. So far I have nearly a whole shelf of a World Coin Typeset, though it is really only a drop in the bucket of what it is out there.

A couple weeks ago I brought my kids to a coin show where every kid under 12 gets a free handful of foreign coins from a big bin near the door. We came home with about 150 new foreign coins, with some dating back to the 1870's. Really cool stuff. I am now in the process of cataloging all of them and putting them in my kid's albums. They always get really excited about them and look on a map to see where they are from. One of my kids is really excited to find any coins with boats on them.

Incidently, for Ultra Rant, there are a LOT of Norway coins in this bin

Anyway, if your miscellaneous foreign coins need a new home, PM me and maybe we can work out a deal.

January1May, thanks for the update on some of your collecting. I should be in Moscow in a couple months, so I will try to bring some things to help you out. I may have duplicates of some of the 10 Ruble military glory city coins you are seeking.

I have more than a few not labeled. After all, the coin is already labeled, right?

I collect stamps from the inflationary period in Germany between WWI and WWII. Its kind of neat to have a 2 million mark stamp. I guess someone needed to mail a letter really bad, lol.

Someone has a set of coins, all of whose dates are prime numbers.

My inner math-nerd just swooned.

@mysilveryears, I can guess-nude figures on coins. And no, don't post them.

Having recently acquired a pentagonal, i.e. 5-sided, coin (good luck finding one of those - Numista lists only three types of circulating pentagonal coins; one of them is the Transnistria plastic that is probably better described as a banknote or token, and I have the larger of the other two), I'm now considering a set of circulation coins with different numbers of sides.

I'd probably need the famous Cook Islands $2 for this set, though (as they're the only circulating triangular types), and that might well cost me a load of money.

Largest number of sides on a circulating coin is, I believe, 24, for some Brazilian issues. I don't have any of those (yet - they're not that rare).
I do have 21 and 22 sided coins (Yemen and France respectively). To the best of my knowledge, there are no 23 sided coins.
As far as I can tell, the only 20 sided coins are Guadeloupe... mind you, I'm probably going to end up getting one of those eventually anyway if I want to make it to 300 countries (currently 264).