Another less know but really promising approach is program synthesis (also called "program generation"). One can build fairly robust model just using 2-5 examples and that too in just seconds. Implementation of this approach is already shipped in to Excel where you just enter few example of formatting and "Flash Fill" will learn what to do: http://research.microsoft.com/en-us/um/people/sumitg/flashfi...

Paper: http://research.microsoft.com/en-us/um/people/sumitg/pubs/ca...