Hidden Markov Models
Papers:
Rabiner -- A Tutorial on Hidden Markov Models and Selected Applications in Speech Recognition
Calvet and Fisher -- Multifrequency News and Stock Returns, 2006
Hassan and Nath -- Stock Market Forecasting Using Hidden Markov Models: A New Approach (2005)
Books and Theses:
Zhang, Prediction of Financial Time Series With Hidden Markov Models (2004 Masters Thesis) -- this thesis claims to "totally beat the stock market" using HMM's.
Other: