Ancient Coinage

Digital Library Numis (Open Access Publications)
Ancient Coinage, Wildwinds
Digital Iconographic Atlas of Numismatics in Antiquity (DIANA)

Historia Numorum. A Manual of Greek Numismatics
Hellenistic Royal Coinages
Seleucid Coinage
Ptolemaic Coinage
Coins of the Kings of Macedonia (Pella)

Coins of the Roman Empire (Ocre)
Roman Imperial Coins - Free online resource for collectors
Roman Numismatic Gallery
Roman Provincial Coinage
Corpus Nummorum Online. Greek and Roman Provincial Coinage
Iron Age Coins in Britain (IACB)
Online Catalogue of Byzantine Coins

Coin Hoards of the Roman Empire (Oxford University)