It seems that any time I try to work on the computer when my son is awake, he wants to be right with me helping out. So we came up with "work" that he can do to: typing his name and the names of the rest of his family members.
This has been so good for his letter recognition skills! And while he used to need me to prompt him with each letter to type, he is now able to say all the letters in his name and at least the beginning letter for the rest of our names.
He still needs lots of supervision and occasional promoting, and our "typing" sessions last a max of 10 minutes each, but it's a time we both enjoy.