No, I don't mean making your baby do worksheets LOL! But very little ones can learn sign language, and even letters and sounds and numbers... colors... things like that. Sign language helps them to be able to communicate before they can talk, which can help lessen frustration.
I used Leap Frog DVDs to help my children learn letters and their sounds and numbers. And, of course, reading to your children will help in many ways - both with learning language and with security, because ANY time you spend time with your child, it helps!