Dynamic Graphical models (including hidden Markov models, Dynamic Bayesian networks, and temporal conditional random fields) are a general statistical abstraction for time series that are widely used in speech recognition, language processing, bio-informatics, and other time-series applications. Such time series, however, have properties that introduce unique research problems. The first part of this talk will present a variety of graph structures that solve many problems in these areas. Next, we will outline the computational challenges in applying this framework on very large problems. We will describe novel exact and approximate inference procedures for computing with these models which involves, perhaps as expected, graph triangulation, conditioning, and search procedures, but perhaps more surprisingly, also involves optimal bin packing, max-flow procedures, and other graph cut problems.