Right now, only shuffle, linear-loop, linear and random-by-age-and-rating (which is fired by pressing both the repeat and shuffle buttons in the gui...) are available from the gui, it would be great to replace the repeat and shuffle toggles from the toolbar by a play-order combo containing Normal, repeat Song, repeat album, Random song, Random Album, and Advanced play order.
Now, Advanced play order would pop up a dialog, where the user could choose to advance based in single tracks, albums or artists, and play those ordered by some parameter (track number, (average) rating, name, etc) or randomly prefering either the ones that have not been playing in a while, the higher rated, the most played ones, or none.