  The formation and evolution of disk-dominated galaxies is difficult to
explain, yet these objects exist. We therefore embarked on a study aimed at a
better understanding of these enigmatic objects. We used data from the SDSS DR1
in order to identify edge-on galaxies with disks in a uniform, reproducible,
automated fashion. We identified 3169 edge-on disk galaxies, which we
subdivided into disk galaxies with bulge, intermediate types, and simple disk
galaxies without any obvious bulge component. We subdivided these types further
into subclasses: Sa(f), Sb(f), Sc(f), Scd(f), Sd(f), Irr(f), where the (f)
indicates that these galaxies are seen edge-on. A number of incompleteness
effects affect our catalog, but it contains almost a factor of four more
bulgeless galaxies with prominent simple disks (flat galaxies) within the area
covered here than previous optical catalogs, which were based on the visual
selection from photographic plates. We find that approximately 15% of the
edge-on disk galaxies in our catalog are flat galaxies, demonstrating that
these galaxies are fairly common, especially among intermediate-mass
star-forming galaxies. Bulgeless disks account for roughly one third of our
galaxies when also puffy disks and edge-on irregulars are included.(Abridged)
