[Inziladun]

Originally Posted by Legate of Amon Lanc

As for most of the kingdoms of Men, I guess that's just what you said - the silver pennies, I am not aware of any other mention of currency elsewhere. We can only speculate if there was more or less unified currency (perhaps left from the Númenorean times), or if other kinds of people had different currencies of their own. It would make sense, in my opinion, if the more "primitive" nations of Men had simpler sort of barter-systems, somewhere using different things than money as the "currency" (as in, it used to be e.g. silk in some nations in the past in our world, and so on); and those who came in contact with the Dúnedain (so in time of LotR, the lands which used to be the provinces of Gondor and Arnor, including Hobbit-lands

Well, there is at least one other mention of coinage in LOTR: curiously enough it also occurs in Bree. Gandalf evidently gave a "gold piece" to Butturbur out of relief that Aragorn had found the Hobbits there.

The fact that gold and silver coins were used in Bree (and probably the Shire, too, since we have many mentions of "money" by the Hobbits) would seem to add weight to the idea that at least the Kingdom of Arnor might have once had a common currency. And in Bree and the Shire, where there was apparently no central government or authority, and thus no "government" workers, only currency trading or bartering would make the local economy workable. I'm inclined to think it was only currency, because of something Butturbur said.

'[Mr. Underhill's] welcome to go where he will, as long as he pays in the morning.'

FOTR At the Sign of the Prancing Pony

No trade or service was expected of Frodo, just payment. There'd been no talk of what service Frodo and his friends could provide, nor of anything they had to trade.
Additionally, I don't recall any reference to banks or counting houses in Bree or the Shire where currency exchanges could be done, and the Kingdom or Arnor had been gone for over a thousand years, so I would think the coins would have been simple metal discs, accepted everywhere the inhabitants of those areas were likely to go.

Originally Posted by Legate of Amon Lanc

As for other races, and earlier times, I can imagine the Dwarves trading for gems and various metal ingots, of which they'd have really abundant amount. Gems and precious metals would be used also in "inter-racial trade", as it seems to be mentioned also in Sil and everywhere. It is worth mentioning that in the Hobbit, Thorin, when explaining the history of Erebor to Bilbo, mentions that the Dwarves under the Mountain used to trade their craft for food provided by the Men of Dale; and it is not clear whether they used money as a sort of means for it or if it was just a sort of barter-trade. Also, I don't know if the Dwarves would have had any need for having a currency among themselves.

The Dwarves who traveled through Eriador at least had some of the gold and silver coins to use in Bree and the Shire, I would think. Else they'd always be hauling around gems and possibly metal-crafted things to trade, and I'd think that would be pretty cumbersome to the traveler.