Wofsy group members, feel free to add more.
STILT, the Stochastic Time-Inverted Lagrangian Transport model, is a Lagrangian particle dispersion model (LPDM) for atmospheric transport.
Official page: http://stilt-model.org/index.php/Main/HomePage
STILT with WRF: http://stilt-model.org/index.php/WRFSTILT/WRF-STILT