  We report on the abundance of interstellar neutral oxygen (OI) for 26
sightlines, using data from the Far Ultraviolet Spectroscopic Explorer (FUSE),
the International Spectroscopic Explorer (IUE), and the Hubble Space Telescope
(HST). OI column densities are derived by measuring the equivalent widths of
several ultraviolet absorption lines, and subsequently fitting those to a curve
of growth. We consider both our general sample of 26 sightlines and a more
restrictive sample of 10 sightlines that utilize HST data for a measurement of
the weak 1355 angstrom line of oxygen, and are thus better constrained due to
our sampling of all three sections of the curve of growth. The column densities
of our HST sample show ratios of O/H that agree with the current best solar
value if dust is considered, with the possible exception of one sightline (HD
37903). We note some very limited evidence in the HST sample for trends of
increasing depletion with respect to the ratio of total to selective extinction
and the molecular fraction of hydrogen, but the trends are not conclusive.
Unlike a recent result from Cartledge et al. (2004), we do not see evidence for
increasing depletion with respect to the average volume density of hydrogen,
but our HST sample contains only two points more dense than the critical
density determined in that paper. The column densities of our more general
sample show some scatter in O/H, but most agree with the solar value to within
errors. We discuss these results in the context of establishing the best method
for determining interstellar abundances, the unresolved question of the best
value for O/H in the interstellar medium (ISM), the O/H ratios observed in
Galactic stars, and the depletion of gas-phase oxygen onto dust grains.
