The media player builtin to Picard should include buttons for Next Track and Previous Track (which should also function as restart current track from the beginning).

It would also be nice if there were buttons to skip forward and backwards a fixed amount of time (like 30 seconds to easily get past intros).  The skip amounts should be configurable too.

In fact, having whether these additional controls are shown should be configurable so people who like the minimal interface (as it is currently) can still have it if desired.