The Hanen Centre is a non-profit that focuses on enabling young children to develop language and literacy skills. The programs must be purchased, but the website still contains a wealth of free information. Check-out the program descriptions and the HELPFUL INFO page.
Check out the PUBLIC tab for information sheets on disorders and treatments as well as links to various speech related resources.
The FOR THE PUBLIC section has good speech related information, likely the most useful is the section on "What do SLPs Do?"
Probably not super useful unless you really want to nerd-out. There are 1000's for technical publications available to the public.
Apraxia Kids is a non-profit focused on improving the lives of children with Childhood Apraxia of Speech (CAS). There is excellent information for parents in the NEW TO APRAXIA and EDUCATION>ARTICLE LIBRARY sections. Great resource for anyone supporting a child with CAS.