Allcoins - A Numismatic Search Engine and Directory
Allcoins is a coin search engine and directory. Numismatics is the proper name for coin collecting. Since Allcoins does not sell or buy coins, they can list all the different sites without bias.
It is an excellent resource for finding information on all types of coins and includes paper money as well. You can find ancient coins, US and UK coins and even links to coin shows and museums.
(This is a sponsored post, but I really recommend it!)
Allcoins.org - The Numismatic Search Engine and Numismatic Directory for Numismatic Information