I'm thinking something along the lines of a DJ 'dual turntable'.
This is not my actual use for it: I know there is professional equipment and software for such uses.
My issue is that sometimes, for example, I would have a playlist or a shuffled queue on hold (paused), but want to quickly listen/browse through a single or couple tracks while I'm editing something, without losing the current queue. Using the 'play next' function doesn't really work with me, since it means skipping the current track or such / fiddling around with the queue in my experience gets quite fiddly.
Maybe an secondary 'now playing' Panel which isn't synced to the main MB player control could be constructed for temporary playing of tracks alongside the main queue.
I'm sure people will just recommend using another 'quick music player' like WMP or something to listen to a single file, but generally other players take a while to load up, and MusicBee is, well... already there, and will be able to access the track quite quickly.
Maybe some people would also use it as a DJing tool.
Since it seems to me that this would be quite a task and not many people might use it, I'm not really suggesting this be in the next version or whatever, but maybe someone can make a plugin that works well. Just my little side wish.