1. Pickles, John. (ed.). 1995. Ground Truth: The Social Implications of Geographic Information Systems. New York: Guilford.
Ground Truth is the one that started it all. As a technician in training, struggling with ethical and subjective aspects of mapping, finding this book on the shelves in the College of New Caledonia's library was a conversion experience. I wrote a paper on ground truth in GIS, which led to subsequent work in indigenous mapping (Wet'suwet'en) and a master's and PhD in the subject.
2. Curry, Michael. 1998. Digital Places: Living With Geographic Information Technologies. London and New York: Routledge.
My best association with this book was a discussion had during the defense of my master's degree with Simon Dalby, Sebastien Caquard, Iain Wallace, and Derek Smith. The Curry text came up again and again. Its citation and use as a theoretical base for my own master's work in northwestern BC was indispensable. It still is.
3. Harley, J.B. 2002. The New Nature of Maps. Johns Hopkins University Press.
This book holds the ur-text of critical GIS, Harley's "Deconstructing the Map" published six years before Pickles Ground Truth. It has several other key, indispensable, texts for critical geographical studies.
4. Wood, Denis. 2010. Rethinking the Power of Maps. New York: Guilford.
I find this text much more comprehensive and credible than Wood's earlier The Power of Maps. Here we have the definitive statement on counter-mapping.
5. Pickles, John. 2004. A History of Spaces: Cartographic Reason, Mapping, and the Geocoded World. London and New York: Routledge.
Pickles second critical GIS text is subtle, and it has the advantage of being a single-authored monograph. It appeared just before the Google Earth revolution, which makes it interesting to read. Pickles missed nothing by this timing.
6. Schuurman, Nadine. 2004. GIS: A Short Introduction. Wiley.
Also pre-Google Earth revolution, it is this text's strength that it focuses on GIS, and the truly critical aspects for thinking that can be taken from that infamous suite of tools so closely associated with ESRI.
7. Harvey, Francis. 2008. A Primer of GIS: Fundamental Geographic and Cartographic Concepts. New York: Guilford.
This is an excellent text with pedagogical impact. It covers GIS and mapping from a very well-grounded base in mapping practices, with sections on ethics of (indigenous) mapping.
8. Cope, Meghan and Elwood, Sarah. (eds.). 2009. Qualitative GIS: A Mixed Methods Approach. London: Sage.
Cope and Elwood's edited volume has chapters by Rambaldi and Corbett; Schuurman; and Matthew Wilson amongst other heavy-hitters in critical GIS.
9. Kurgan, Laura. 2013. Close Up At A Distance. Zone Books.
This book covers geospatial mapping projects over decades, with excellent coverage of GPS mapping as / and art.
10. O'Rourke, Karen. 2013. Walking and Mapping: Artists As Cartographers. Cambridge: MIT Press.
Finally we have a text that covers psychogeography and GPS comprehensively under one cover, from one of my very favourite publishers, MIT press.
(apologies to those left off the list...)