I have not seen this suggested yet but one thing I would like to see is the ability to move a structure that is in the build queue. I will often build a few things then want to move a turret that is in the middle of the queue and have to remove everything in order to change its position.
Note that I do NOT mean change the order of something being built in a build queue (although this is a good idea) but rather to move a structure in space before it begins construction.