I have a mostly-headless HTPC without keyboard, so it is easier to control it remotely. VNC lets you do anything, but for simple things a command line is faster.
My media player of choice is rhythmbox, so there's an easy way to control it: rhythmbox-control. However, it requires an X session and ssh -X opens a new one. Here's how to use it to control a rhythmbox instance that is already running in the main display:
[code]alias rthythmbox-remote="env DISPLAY=:0.0 rhythmbox-control \$1"[/code]
[code]ssh -p 1234 computer.local rhythmbox-remote --next[/code]