Cheap ceiling tiles, such as the kind found in offices everywhere, are not very attractive. Commonly made of polystyrene, they may be washable, water and mold resistant and universally designed to fit pre-existing grids, but they have a sterile look to them. Spruce up the aesthetics of a room with a drop ceiling by decorating plain, cheap tiles.
You can try painting ceiling tiles. Since you only have to paint one side, a can of latex-based spray paint will go a long way. Plus, the room will glow differently thanks to the new color. Another option is to adorn them with interesting fabric. Attaching fabric to the corners of each tile and allowing the center to droop slightly adds a 3-dimensional quality to the ceiling in addition to sprucing up the color.