The Fiddler’s Companion – A huge storehouse of information on traditional music of Ireland, Scotland, the US and Canada. This site is in the process of being converted to a wiki format – see The Traditional Tune Archive, below.
The Session.org – A large repository of traditional Irish music. Includes music notation, ABC files, information on recordings, discussions and more.
Comhaltas Ceoltóirí Éireann – Comhaltas Ceoltóirí Éireann claims to be the largest group involved in the preservation and promotion of Irish traditional music. Their archive contains the recordings, documents and images collected by Comhaltas Ceoltóirí Éireann during their 50 years of promoting Irish music and culture.