  We recently discovered a large number of highly active Be stars in the open
cluster NGC 3766, making it an excellent location to study the formation
mechanism of Be star disks. To explore whether similar disk appearances and/or
disappearances are common among the Be stars in other open clusters, we present
here multiple epochs of H-alpha spectroscopy for 296 stars in eight open
clusters. We identify 12 new transient Be stars and confirm 17 additional Be
stars with relatively stable disks. By comparing the H-alpha equivalent widths
to the photometric y - H-alpha colors, we present a method to estimate the
strength of the H-alpha emission when spectroscopy is not available. For a
subset of 128 stars in four open clusters, we also use blue optical
spectroscopy and available Stromgren photometry to measure their projected
rotational velocities, effective temperatures, and polar surface gravities. We
combine our Be star detections from these four clusters to investigate physical
differences between the transient Be stars, stable Be stars, and normal B-type
stars with no line emission. Both types of Be stars are faster rotating
populations than normal B-type stars, and we find no significant physical
differences between the transient and stable Be stars in our sample.
