Muthén, B., Asparouhov, T. & Rebollo, I. (2006). Advances in behavioral genetics modeling using Mplus: Applications of factor mixture modeling to twin data. Twin Research and Human Genetics, 9, 313-324.
which is on our web site under Genetics Modeling. Another application area is longitudinal data and Latent Transition Analysis - we have several such papers on our web site.