Installing tongue-and-groove (aka T&G) boards is a fast, inexpensive way to panel any ceiling or wall. You can install T&G over bare framing, drywall or plaster, so it's a great cover-up for an ugly ceiling.
How to Install a Tongue-and-Groove Plank Ceiling - DIY Network (We did this in our sunroom. But since we were covering a damaged ceiling, we skipped the furring strips step and glued the planks directly to the ceiling with a couple of finishing nails from a staple gun to hold them up until the glue dried. This really sped up the process and we knocked the whole thing out in a day. Then we primed/painted and installed trim. It's holding up well and looks great!)