Ancient Celt-Iberian, Iberian and Punic Coins
In this site, you can find info about ancient coins minted in Hispania (native, greek , punic and roman provincial coins). Site in English and Spanish.
The Celtic Coin Index
A project sponsored by Oxford University. Good background information, and promises that soon the entire 28,000 image index will be made public.
The Kernunnos Web Pages
Site about pre-Christian Celtic history and modern Druidry, with a nice emphasis on Celtic coins.