ACSEARCH.INFO Ancient Coin Search Engine. A database created by Simon Wieland, Lars Rutten and Markus Beyeler.
BEAST COINS Many information for experienced collectors and also for novices. The subpage "Not in RIC" was the first inspiration for my project.
CLASSICAL NUMISMATIC GROUP Invaluable "Research" section. Should be a model for other numismatic dealers.
CONSTANTINE THE GREAT COINS Great page created by Victor Clark. All you need to know about bronze coinage of one of the most influential Roman emperors.
FORVM ANCIENT COINS Tools for identifying coins, articles and excellent discussion board.
HELVETICA'S IDENTIFICATION HELP PAGE Created by Dane Kurth (Helvetica). If you can't afford RIC, you can use Helvetica's spreadsheets instead.
NVMMVS BIBLE II Probably the biggest database of Roman coins minted from 313 to 476.
WILDWINDS Very popular catalogue of Roman coins created by the late Dave Surber (now administrated by Helvetica). RIC numbers, inscription search and many more.