New book by Hartshorne
A series of arxiv preprints by Orlov.
http://mathoverflow.net/questions/40574/innovations-in-deformation-theory
Jonathan Wise: Obstruction theories and virtual fundamental classes. http://front.math.ucdavis.edu/1111.4200
Thesis of Illusie
Introduction to singularities and deformations, Greuel et al, Springer
http://nlab.mathforge.org/nlab/show/deformation+theory
http://mathoverflow.net/questions/5364/what-is-a-deformation-of-a-category
http://mathoverflow.net/questions/570/deformation-theory-of-representations-of-an-algebraic-group
Greuel et al: Introduction to Singularities and Deformations (Springer Monographs in Mathematics)
Green, Griffiths: Formal Deformation of Chow Groups. In Abel volume.
http://mathoverflow.net/questions/33526/deformations-and-the-dual-numbers
nLab page on Deformation theory