I was cleaning out my office last week and found two old keyboards that we no longer use. I was about to toss them in the "freecycle" pile, when I realized they could be a fun toy for the kids. R loved the noise of just pounding on the keys, but there are a lot of ways this could be an educational toy for your tot.
Music - Put on some music and have your tot try to match or compliment the beat using the keyboard. Or pull out a variety of play instruments and have a concert!
Alphabet- Review the letters, having your child find each one as you call them out. If your child has learned the letters in order, this is a great way to see if they know them when they are all jumbled up like on a QWERTY keyboard.
Numbers - Same as above, except with numbers.
Pretend Play - Set up a pretend office for your child on a little table. A keyboard, square piece of cardboard as a "screen", plastic coffee cup, pen and paper, and pretend phone would be a fun little play center!