The advent of massive wide-field variability surveys continues to lead to disocveries of rare and often unexpected new classes of transients. Perhaps the best known group of such object is the class of superluminous supernovae (SNe). Our group pioneered the studies of SLSNe (for example these papers by Ofek et al., Gal-Yam et al. and Quimby et al.) and continues to work on this subject, most recently mainly on studies of samples of events, e.g., the large sample of SLSNe from PTF. A semi-popular acrticle on SLSNe and their discovery can be found here.
Another group of exotic explosions we discovered is a class of faint explosions that eject relatively little mass whose composition is remarkably rich in calcium (and thus commonly named calcium-rich events). A very unusual property of these events is their tendancy to occur in teh remote outskirts of galaxies, which may suggest an origin in an old population of stars that may also need to by quite low-metallicity.
Our work on optical transients also led to one of the first systematic papers on transients occurring in galactic nuclei that are good candidates to be the predicted flares from tidal disruptions of stars by nuclear massive black holes. In particular, this work highlighted the remarkable tendency of these events to prefer a certain rare type of galaxies ("E+A") which may be a major clue about the processes leading to stars falling into massive black holes.