  We present a new catalogue of variable stars compiled from data taken for the
University of New South Wales Extrasolar Planet Search. From 2004 October to
2007 May, 25 target fields were each observed for 1-4 months, resulting in
~87000 high precision light curves with 1600-4400 data points. We have
extracted a total of 850 variable light curves, 659 of which do not have a
counterpart in either the General Catalog of Variable Stars, the New Suspected
Variables catalogue or the All Sky Automated Survey southern variable star
catalogue. The catalogue is detailed here, and includes 142 Algol-type
eclipsing binaries, 23 beta Lyrae-type eclipsing binaries, 218 contact
eclipsing binaries, 53 RR Lyrae stars, 26 Cepheid stars, 13 rotationally
variable active stars, 153 uncategorised pulsating stars with periods <10 d,
including delta Scuti stars, and 222 long period variableswith variability on
timescales of >10 d. As a general application of variable stars discovered by
extrasolar planet transit search projects, we discuss several astrophysical
problems which could benefit from carefully selected samples of bright
variables. These include: (i) the quest for contact binaries with the smallest
mass ratio, which could be used to test theories of binary mergers; (ii)
detached eclipsing binaries with pre-main-sequence components, which are
important test objects for calibrating stellar evolutionary models; and (iii)
RR Lyrae-type pulsating stars exhibiting the Blazhko-effect, which is one of
the last great mysteries of pulsating star research.
