  Updates of electroweak single top quark production measurements by the D0
collaboration are presented using 5.4fb^-1 of proton-antiproton collision data
from the Tevatron at Fermilab. Measurements of the t-channel, s-channel and
combined single top quark production cross section are presented, including an
updated lower limit on the CKM matrix element |V_tb|. Also reported are results
from searches for gluon-quark flavor-changing neutral currents and W' boson
production.
