  Gravitational lensing by a spiral galaxy occurs when the line-of-sight to a
background quasar passes within a few kpc from the center of the galactic disk.
Since galactic disks are rich in neutral hydrogen, the quasar spectrum will
likely be marked by a damped Lyman-alpha absorption trough at the lens
redshift. Therefore, the efficiency of searches for gravitational lensing with
sub-arcsecond splitting can be enhanced by 1-2 orders of magnitude by focusing
on a subset of all bright quasars which show low-redshift (z<1) strong
Lyman-alpha absorption (N>10^{21} cm^{-2}}). The double-image signature of
lensing could, in principle, be identified spectroscopically and without the
need for high-resolution imaging. The absorption spectrum of a spiral lens
would show a generic double-step profile due to the superposition of the two
absorption troughs of the different images. Finally, we note that searches for
microlensing signatures of quasars with damped Lyman-alpha absorption could
calibrate the fraction of MACHOs in galactic halos at high redshift.
