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:
