I am using Vectir PC remote control as a remote control on my Nexus S 8.4. It controls the mouse, keyboard, volume and a number of media players. I use it as a remote control for Spotify, VLC and WMP on my HTPC. One problem with using a tablet as a remote control in a dark HTPC environment is the screen can be really bright. The dark theme in Vectir remote control solves this problem. Give it a go. The free version has pretty much everything you will need.