The Indo-European Etymological Dictionaries Online (IEDO) reconstructs the lexicon for the most important languages and language branches of Indo-European.
It is a rich and voluminous online reference source for historical and general linguists. Dictionaries can be cross-searched. Each entry is accompanied by grammatical info, meaning(s), etymological commentary, reconstructions, cognates and often extensive bibliographical information. New content will be added on an annual basis.