Starting today you can um, truth be told I have absolutely no idea what it does. It sounds music related, I think.
“A metronome is any device that produces regular, metrical ticks (beats). These ticks represent a fixed, regular aural pulse; some metronomes also include synchronized visual motion (e.g. pendulum-swing). The metronome dates back to the early 19th century. Though the metronome was conceived as a tool for music, some musicians consider it to be a highly controversial tool in this respect (see Criticism of metronome use): there are musicians who reject the metronome altogether.”
Metronome for Zune HD is available free right now in the Zune Marketplace.