If you have a bathroom or kitchen with cabinets that look well worn, you can remove the cabinet doors (and save them for when you are feeling ambitious enough to paint them!) and make simple fabric covers for your cabinet spaces instead.
First, you want to measure the size of the windows. You will want to add 2″ in the height and a few extra inches in the width, depending on how you want the fabric to lie across the opening. You will use that as your template. You can use all kinds of fabric for the fabric doors, and a salesperson will be able to help you determine how much fabric you need based on the fabric width.
Be sure that you pre-wash your fabric if you want to be able to wash them later if they get dirty or dusty.
You will want to hem the two sides at 1/2″. Then, you will want to hem to top and bottom using a 1″ hem, so you have plenty of room for a small curtain rod to go through.
At your local hardware store, you can buy either doweling or small diameter curtain rods. You can fasten them to the outside using one of a cariety of fasteners, from the simple and inexpensive to the truly glam. Then, with a drill or screwdriver, fasten the rod on one side, feed the fabric door through the rod, and fasten the other side.
Now, to use, simply pull to one side or the other to use.