A Guide to Structure Prediction: (version 2.1)
Applications of 1H NMR spectroscopy: Proton structure elucidation written by P. Hallpap, H. Händel. Excellent work and very good for the beginner.
Organic Structure Elucidation Workbook: A set of NMR stucture determination and assignment problems, easy, moderate and hard. (Select "problems" from left frame)
Proton NMR Tutorial: Tutorial and exercises on nuclear magnetic resonance.
WebSpectra - Problems in NMR: More NMR practice problems and a great outline of spectral assignments methods.