Das Wikiwörterbuch ist das deutschsprachige Wiktionary: ein frei verfügbares, mehrsprachiges Wörterbuch für den Wortschatz aller Sprachen. Es existiert seit dem 1. Mai 2004
The Indogermanisches Etymologisches Wörterbuch (Wikipedia) by the Jewish-Czech scholar Julius Pokorny was published in 1959. The work is now slightly outdated, especially as it was conservative even at the time Pokorny wrote it, ignoring the laryngeal theory, and hardly including any Tocharian or Anatolian material. But there exists no more modern and updated etymological dictionary of the Indo-European languages, so it is still of interest to scholars.
O. Ferret, and M. Zock. ACL '06: Proceedings of the 21st International Conference on Computational
Linguistics and the 44th annual meeting of the ACL, page 281--288. Morristown, NJ, USA, Association for Computational Linguistics, (2006)