  The angle between the rotation and orbital axes of stars in binary systems --
the obliquity -- is an important indicator of how these systems form and evolve
but few such measurements exist. We combine the sample of astrometric orbital
inclinations from Gaia DR3 with a sample of solar-like oscillators in which
rotational inclinations have been measured using asteroseismology. We
supplement our sample with one binary whose visual orbit has been determined
using speckle interferometry and present the projected spin-orbit alignments in
five systems. We find that each system, and the overall sample, is consistent
with alignment but there are important caveats. First, the asteroseismic
rotational inclinations are fundamentally ambiguous and, second, we can only
measure the projected (rather than true) obliquity. If rotational and orbital
inclinations are independent and isotropically-distributed, however, the
likelihood of drawing our data by chance is less than a few per cent. Though
small, our data set argues against uniformly random obliquities in binary
systems. We speculate that dozens more measurements could be made using data
from NASA's TESS mission, mostly in red giants. ESA's PLATO mission will likely
produce hundreds more spin-orbit measurements in systems with main-sequence and
subgiant stars.
