Coffee and tea stains can be removed from light-colored cups and mugs by using a damp sponge dipped in baking soda. If the spots are proving stubborn, try rubbing them with a bit of salt.
If you have rust and mineral deposits on a teapot or an old stovetop-style coffee percolator, they can be removed by filling the pot with water and adding 2 tablespoons baking soda and the juice from half a lemon. Gently boil for 15 minutes, then rinse thoroughly. If you want to get coffee and mineral stains out of the glass or stainless steel pot of your coffeemaker, try this variation: Add 1 cup crushed ice, 1 tablespoon water, and 4 teaspoons salt to the pot when it is cold, swish around, and then wash as usual. Again, for really stubborn stains, substitute regular table salt with coarse salt.
Many of these methods can also be used for cleaning blenders and food processors. The baking soda will help get rid of any lingering odors from foods like peppers or garlic, and the salt and ice will help clean the blades as they "chew" them up. Rinse the blades thoroughly and let them dry, or run through the dishwasher if necessary (and if possible).