Nimzo Books and Videos
Easy Guide to the Nimzo-Indian, Emms (Cadogan 1998)
Lack of modesty prevents me from giving this book an objective review, so instead I'll give it a shameless plug. Written chiefly as a quick and easy guide for the black player, I give a repertoire containing 4...0-0 against the Classical and 4...b6 against the Rubinstein, plus all the main lines against White's other choices.
Nimzo-Indian Defence Classical Variation, Ivan Sokolov (Cadogan 1995)
Written by one of the World's leading experts on 4 Qc2, this book is the most recent work on the popular Classical Variation. All variations are covered, and despite being four years old now, the book has aged quite well (many of the lines and their assessments hold true today).
Nimzo-Indian 4 e3: Nimzowitsch, Hubner and Taimanov Variations, Pritchett (Batsford 1980)
Now sadly out of print, this excellent work by the Scottish IM Craig Pritchett was an inspiration to me, and the main reason I began playing the Nimzo. The book concentrates on the Rubinstein Variation, studying the Black replies 4...b6, 4...c5 and 4...Nc6.
The Nimzo-Indian Defence, Gligoric (Cadogan 1993)
With 338 pages, this is one of the most comprehensive books on the Nimzo around. Each and every line of the Nimzo is covered and I'd say that the book's strength lies in its study of the Rubinstein Variation, which is very extensive. The only grumble I would have is that its coverage of 4 Qc2 amounts to only one tenth of the book, which is a bit skimpy for White's most popular choice at GM level.
Mastering the Nimzo-Indian, Kosten (Batsford 1998)
Part of the Batsford "Read and Play Method" series, where much more emphasis is put on the pawn structures and relevant plans for both sides, rather than the nitty-gritty of the actual theory. This book works best in conjunction with a more theoretical work, or an openings encyclopedia.
Nimzo-Indian Defence, Ward (GM Video, 1998) - Buy the video here.
In this entertaining video, Ward chooses a repertoire for Black based on his own games with the Nimzo-Indian. This includes the tricky 4...b6 against the Rubinstein and the sharp 4...d5 against the Classical.