I believe most users of the sleep timer function almost almost always use it for the same amount of time each night. For example, I always set it for 15 minutes. Then I go to sleep.
It would be nice for the sleep timer button on the Playing Tab to just use the previous time it was set for by default.
Therefore if you tap the Clock icon, it will set the sleep timer for the setting used previously.
Suggestion:
Tap Clock Icon = Set Sleep Timer to last used setting (example 15 minutes)
Tap+Hold Clock Icon = Bring up Sleep Timer menu to select time
+1 - would be awesome.
Also, if you could also broadcast an intent that would set the timer. (think a shortcut or a custom widget)
That's a good idea, I created an issue for this - http://mantis.snoggdoggler.com/view.php?id=1737