I use this app in my workplace all the time- I work with children- some of which are deaf or non-verbal autistic...this allows me to interpret what theyre saying while learning the sign for next time, and/or introduce new words into their vocabulary- which has makes the kids much more willing to work with me. Theyre very respectful of my iPod touch because they know its how to get themselves understood! Excellent teaching/learning tool.
Navvan about Sign 4 Me