Information on articulation and phonology:
http://www.asha.org/public/speech/disorders/SpeechSoundDisorders/
Typical Language Development for children in elementary school:
http://www.asha.org/public/speech/development/communicationdevelopment/
Childhood Apraxia of speech:
http://www.asha.org/public/speech/disorders/ChildhoodApraxia/
Stuttering Foundation: