One neat idea is electrostatic speakers! They're one of the more exotic speaker types, but have unparalleled quality at low volumes. However they are prone to distortion as volume increases and require high (100+) voltage supplies. They can be dangerous and fragile.
The idea is you stretch a mylar film very tightly into a rectangle, and then sandwich it between two metal meshes, with an air gap. By putting voltage on the meshes, static electricity pulls the mylar forward and back while keeping it almost perfectly flat.
You can put meshes (or ITO films) inside a double pane window to create a very even force over the whole window, making it an excellent transducer. It requires far higher voltages to move glass, though. Putting mylar in between the panes doesnt work (you need some free space to create proper cancellation- oversimplifying) and putting mylar on the outside is dangerous. Tricky problem.
The even bigger concern is mostly that a moderately loud speaker system (>50-150 watts) can electrocute you. I mean that literally, as the portmanteau of electricity and execution. 1 kV is easily enough to put electricity through your heart; 50 milliamps would be lethal. 50 mA at 1 kV is only 50 watts, less than a laptop charger. A big set of electrostatic speakers can just stop your heart if you're very unlucky.