I work mainly with the Indo-European language family, in particular Tocharian, an extinct language of the Indo-European family spoken in spoken in Eastern Central Asia. I am also a specializing on the Indo-Aryan sub-branch, in particular the Romani group. Further, I have worked on Amazonian languages, in particular of the Tupí branch.
Currently, I am project leader and editor/database manager for a project that aims at compiling big data sets for reconstructing linguistic prehistory of the areas Europe and the Amazon, with a focus on the Indo-European, North-East and North-West Caucasian, Kartvelian, Tupí and Arawak language families. All data is publicly available via the infrastructure:

Diachronic Atlas of Comparative Linguistics
Another project aims to produce a paper and electronic dictionary of Tocharian A.
Besides, I have worked on langage contact between Scandinavian, Romani, and secret languages, as well as sound symbolism in Germanic languages.  See Publications.