We have dark oak cupboards and would like to lighten or paint them. Lightening them would be preferable. Is this possible and what materials should we use?

You can do either, depending on how much time and energy you have. Whichever option you choose, first remove the doors and clean thoroughly to remove dirt and grease, and then sand. If you decide to paint, melamine does a good job and is very durable. Use a high-density foam roller and dry thoroughly between coats. The only negative is the strong smell. You can also use a good quality latex paint in a pearl or semi-gloss finish. If you decide not to paint, use a chemical stripper such as Dad's Easy Spray or Circa Furniture Stripper and then sand. Sanding is extremely important, because all products will raise the grain of the wood. Again, if fumes are a concern, use an organic stripper such as Organic Strip, which sells for $20/quart. The next step is to use a two-part bleach kit such as Wood-Kote. This is a good product because you don't have to use the whole kit at once and only mix up what you need. It costs $25.00. Safety is an issue using these products. Be sure to read the manufacturer's directions carefully and wear goggles, gloves, and protective clothing. If you like the colour after bleaching, finish with acrylic polyurethane such as Stays Clear by Benjamin Moore, which resists yellowing. If you're still not happy with the colour after bleaching, apply a pickling white penetrating stain ($14.95/litre) and then finish with Stays Clear.