When Munchkin was about 5 months old, I found the Baby Signing Time DVDs. At first I thought, "Wow, If this really works, I am going to have a pretty awesome parlor trick on my hands! I bought the Baby Signing Time 2 disc DVD/ 2 CD set from www.Mom4life.com. These DVD's were created by Rachel Coleman for hearing children to learn signing in a fun way.
We started watching them and the first sign I tried to teach him was the sign for milk. Every time I nursed Munchkin, I would take his hand and help him make the sign. Much to my surprise, after 2 or 3 months he actually started signing. We ended having success with many signs including milk, more, please, and hurt. Hurt was particularly useful when Munchkin had an ear infection and he was able to tell me that his ear hurt!
Now with Pumpkin, we've had even more success. He knows the signs for more, milk, drink, eat, and please. In fact there have been times where he has given me this angry look and forcefully brought his hand to his mouth in the sign for eat. (Pretty much telling me- "Hey you! I'm Hungry!!")
Baby Signing Time has helped us avoid frustration and I even think it may have helped my boys to learn how to talk.
http://www.signingtime.com Check them out. They often send out coupons codes in their newsletters and I've seen some signing time music videos on nickjr.
Disclaimer: I am not affiliated with Baby Signing Time or Mom4life.com. These products were purchased by me for my own use. These are simply my opinions on a product that has been very useful to me.