I started to teach my daughter to sign when she was just an infant, because I wanted to be able to understand what she wanted! She used to sign "more" all the time, so I knew when she wanted more food, more play, etc. Now she signs "food" all the time. As a mom, that is so nice to know when she is hungry. I don't have to guess why she is fussing.
My Baby Can Talk is a great fun video that teaches kids to sign. The recommend it for ages 10 months and up. For more details or to enter to win a copy of this, visit my post on My Baby Can Talk on my blog.