There are many websites that are of use to people interested in the history of Ceredigion. Some of the more obvious ones are:
Ceredigion Archives: The main repository for public and private records relating to Ceredigion.
Ceredigion Museum: Housed in the old Colosseum Cinema in Aberystwyth, and full of fascinating objects relating to the history of the county. There is also a separate site that has images of some of the objects in the collections.
National Library of Wales: Although focused now on collections of national importance, there are many archives and books of particular interest to those interested in Ceredigion.
The Royal Commission on Ancient and Historical Monuments of Wales: A large collection of information relating to the history of the buildings of Wales, including Ceredigion.
Ceredigion Local History Forum: Group who bring together all the local and family history societies and similar organisations in the county.
Pint of History: is a project about pubs. Pubs in Ceredigion. Old pubs, new pubs, beer houses, ale houses, taverns, inns, hotels, railway waiting rooms and breweries.