Indo-European Home Page - Links to various projects involving the Indo-European language, maintained by Dr. Deborah W. Anderson, Dept. of Linguistics, UC Berkeley.
The Indo-European Mailing List - Web-searchable archives of a mailing list devoted to the discussion of Indo-European linguistics and archaeology.
Indo-European Studies - Collection of links to sites and books dealing with Indo-European studies.
Knowing Words in Indo-European - Exploration of the etymology of words related to the word "know" in the Indo-European languages.
Numerals in Indo-European Dialects - Comparative presentation of the numerals 1-10 in the Indo-European languages, including reconstructions in Proto-Indo-European and various intermediate proto (reconstructed) languages.
Sorin Olteanu's Linguae Thraco-Daco-Moesianae (LTDM) Project - This incomplete site is devoted to information on ancient Indo-European languages spoken in the Balkans: Thracian, Dacian and Moesian. It also includes a corpus of Greek and Latin sources, as well as information on ancient Balkans geography, and possible substratum influences on Albanian, Romanian, and Bulgarian, and etymological information on Romanian.
TITUS - Thesaurus Indogermanischer Text- und Sprachmaterialien - Collection of scholarly material devoted to Indo-European linguistics, from the Institute of Comparative Linguistics of the Johann Wolfgang Goethe-Universität, Frankfurt am Main, and related institutions [Multilingual site, includes English-language material]
WordGumbo: Comparative Indo-European - An interesting hodge-podge of pages on various branches and individual member languages of the Indo-European family. There are vocabularies of "lesser-known" languages, and links to major on-line dictionaries of better-known ones.