There are many music players available on Linux and other platforms, I wrote about that earlier. One that stands out from the crowd regarding it’s architecture is Music Player Daemon (or just mpd). It follows the client server model, where the daemon is a music server and you can connect various clients to control the music playback. It’s not the easiest to set up in Ubuntu but with this small guide it should work.
On the desktop (either on Windows and Ubuntu/Linux) it’s easy to install Dropbox and remove it as well. Lately I installed Dropbox on Ubuntu Server, where there is no GUI and no integration with Nautilus. I followed this guide to install and set it as a service on boot. However the same guide(s) does not explain how to properly remove it and I couldn’t find that info on Askubuntu in a quick search.