Here is a model that should be useful to a great many people. The model analyzes data in which the abundance of a target species is recorded over multiple surveys when the species is imperfectly detected. The original paper describing the model is Royle, J.A. 2004. N-Mixture Models for Estimating Population Size from Spatially Replicated Counts. Biometrics 60, 108-115. This exercise was co-written with Heather McKenney from the University of Vermont.