A useful tome to have around to be able to dip into has been the 600
page Companion to Digital Humanities, edited by Susan Schreibman, Ray
Siemens & John Unsworth and published by Blackwell in 2004.

'Humanities Computing' has trouble with maintaining a credible,
distinctive position in the field of academic disciplines ~ such trouble
is in common with that experienced by other 'new', developing
disciplines - Computer Science in the past, and Educational Technology.
This book offers justifications, examples and debate about what does
make it a creditable discipline.

A 600 page book is difficult to read in one sitting, or even in the few
days / weeks / months that one can borrow it from a library - and
difficult to carry around (books - 'portability' still accounts for much
of the popularity of this 'old' medium). But now, when you want to find
some learned words on what can be offered any particular corner of
Humanities endeavours, be it research or teaching&learning, the
Companion is available online at:
http://www.digitalhumanities.org/companion/.