I am learning sign language so that I can teach my 6-month-old son to "talk" to me. It is easy and fun. You may also want to sign to your kids even when they grow older and start to talk. For example, in a noisy place where they can not hear you. Additionally, my instructor told me that sign language can also improve baby's communication skills. Don't forget to talk to them,meaning pronounce what you sign. You also want to show them what you sign by pointing or by showing.
This is my favorite link:
http://saragreene.org/asl.phpEnjoy.