Leap Frog - Letter Factory (toddlers can have it down at 2)
Talking Words Factory (3-4)
Rock n Learn - Colors, Shapes and Numbers (toddlers)
Phonics I & II (3-4)
Spanish I & II (for older kids, but the litte ones love it and pick it up)
I can't recommend any of these high enough. These are instrumental in helping my kids have their phonics down by age 3 and reading by the age of 4.