I agree with the sign language! I started with my 2 year old when she was a baby, and have already started signing to my 3 month old. My 2 year old (2years 4 months) has as many words as many of the first graders I have worked with. Now she may just be a chatty cathy, but I think it is because she was able to understand the principles of communication at a young age. I actually write about baby sign language for an online paper.
Learn and teach a few signs for things he might want eat, drink, play, potty, etc. Even though these are words he probably already knows, when he gets upset he may have trouble with the words. We have had many times where our daughter has had a total meltdown over something she could have easily told us about and it would have been fixed. But two year olds (or almost two year olds) have fits (who knew?) and it makes it difficult for them to communicate at those times. Anyway because of the signs we knew what she wanted and were able to calm her down by telling her we knew she wanted ____ if she could calm down and ask for it properly she would get it. The hardest is when she is just upset and signing "more" More what? haha
ADDED: Sign Language does NOT delay speech development!!!! It's the exact opposite. It teaches children to communicate when they are not able to voice the words. They actually learn words quicker and have a better understand of how language and communication work. I have done extensive research on the subject and my own two year old is proof. That child never stops talking!!! She still signs, but it has almost completely been replaced with vocalizations. It's so cute when she does both at once. She also uses the signs at times where I can't hear/understand her. Sometimes she'll say something that I won't quite undersand and she'll throw out the sign for it and I'll get it instantly. Or the other weekend at church she signed something to me instead of saying it, becuase she was being quite. It was adorable.