It was my great pleasure to sit on the PhD defense committee for the successful defense of Sarah Pearson. She wrote a thesis about low-mass galaxies and globular clusters, considering both their interactions with each other, and with the bigger galaxies into which they later fall. She has some nice analyses of the Palomar 5 tidal stream, and what it's morphology might tell us about the Milky Way halo and bar. And also nice results on gas bridges and streams around pairs of dwarf galaxies.
I was most interested in her stellar-stream results, including several things I hadn't thought about before: One is that prograde streams are more affected by the bar and spiral arms in the disk than retrograde streams. Another is that we might be able to find globular-cluster streams around other galaxies nearby. That would be incredible! And since (as she showed) you can learn a lot about a galaxy just from the shape of a stream, we might not need to do much more than detect streams around other galaxies to learn a lot. It was a pleasure to serve on the committee, and it is a beautiful body of work.