DDI Vantage: Early Intervention - the local early intervention program, serving Salt Lake, Tooele, and Duchesne Counties. Useful for in-home treatments of developmental delays, speech, etc. Serves children under the age of 3, with transition services with the local school districts. Also offers a structured play class if and when a child is ready for that kind of treatment.
Pediatric Rehabilitation Services (through IHC and/or Primary Children's Hospital, various sites throughout the Valley) - speech therapy, occupational therapy, feeding therapy, and more.
RISE Intercept: Mental Health and Behavioral Services - Intercept providers specialize in behavioral therapy, and use the unique method of treatment at the patient's house rather than in an office.
Autism Council of Utah - great local resource organization.
Utah Parent Center - another great source for local resources. They also offer services such as counseling, parenting classes, education advocates, etc.
Autism Speaks - this is a national organization, but one with fingers in a lot of pies so to speak (but in a positive way!). They have information, resources, connections with researchers, local resources, the medical field, you name it. You could spend a week or two on their site and still not see everything.
Easter Seals - another national organization with local sites, dedicated to serving the disabled community and their families.