I made this because it makes queueing tracks more in line with how I use foobar. Allows me to just start playing whatever I feel like and keep queueing songs into a playlist without having to drag and drop and switch around playlist tabs a thousand times.
Non-exhaustive description: http://zyl.pestermom.com/projects/software/foo_smart_queue.html
My first thought was "has he not seen the playback queue?" but after reading the description of what it does and why playback queue doesn't work for you, this is actually pretty cool. Nice work.
This would probably conflict with other queue showing/editing components (like foo_queuecontents). Not a big problem, I guess you should use one or the other.