I've looked into quite a few options as I try to familiarize myself with what's available just for my child w/ special needs. (Yes, I've done this with the sibs in mind, too.)
I began with what I think is the obvious. Autism Society chapter. ARC chapter. Developmental Disability Council. TACA (Talk About Curing Autism). Generation Rescue Angels. Autism Research Institute's list of DAN! doctors.
Yahoo Groups and Google Groups. Go to the groups dot yahoo dot com and groups dot google dot com pages and search for groups on the topic of your child's special need. You'll need a Yahoo ID and Google ID to join the groups. Be sure to think outside the box on your searches. You can search "autism" and "special needs" and "ADHD" alongside the name of the state, and search again with those words next to the city, and yet another search with the name of the county in the search box. If your child has a special interest, be sure to search for that along with the city name and county name. If your child loves trains, there may be a yahoo group for train collectors in the city where you are going. If your child participates in a sport, be sure to connect there, too. I found more help from homeschool groups than I did from autism groups in the area we are headed. And I found more insight from celiac groups than I did from autism groups. When you connect with a group, head over to facebook to look for that group there. There are groups with members from all over the world that may be helpful; one example is the yahoo group "taca-usa", where you may post about a particular state or city and connect with other parents near your destination location. I found names of doctors to research from that particular group. And while you're looking at yahoo and google groups, don't forget to search for special ed law and IEP groups. If your child is going to a public school, make sure you join the yahoo group, IEP_Guide, where you can ask questions about specific states and cities.
Newspaper and TV station web sites in your destination city. Use the search box to search for "special needs" or "autism" on the local media web sites. Take notes. Write down any organization name that is featured. Write down the name of parents who are interviewed. Head over to facebook to try to locate those organizations or parents. Send the parents a private message explaining who you are, why you are intruding on their facebook inbox, and ask for insight about the area you are moving to.
Churches in your destination city. Look for special needs Sunday Schools or Buddy Breaks or something similar. E-mail church staff, introduce yourself, explain your situation, ask for insight.
Jewish Community Center and Friendship Circle in your destination city. (I am spoiled by my current city's offerings; looks like the destination city hasn't gotten involved in the special needs FC thing yet. I'm trying not to be disappointed with all the things I am not finding at our new location.)
The YMCA in your destination city.
TOPSoccer. Miracle League Baseball. Special Olympics. The county park & rec department.
The Chamber of Commerce in your destination city. Chamber employees know a lot about all sorts of topics and know someone who can help you with just about any question or concern. Our Chamber contact turned out to be a bit of an insider to the community of special needs families.
Facebook. The search options are huge here. In the search box at the top of your facebook page, type in the state name and the special interest of your child or his/her diagnostic label. If your child is on a GFCF diet, search on facebook for "gluten free" in that city, county, state.
Next, try a google search with any colleges or universities in your new town or area alongside your child's disability. I was expecting to find programming for kids with autism (which is popular here, but notsomuch there, where we are going). Schools with a speech-language path program may offer free or low cost speech therapy. You may find OT, PT, speech, social skills, rec classes, arts and crafts, sports, etc, at a university. I turned up a couple of college professors who are married to one another who have a child on the autism spectrum that way. I found their e-mail addresses and phone numbers in the faculty section and contacted them to ask for insight as we prepare to move. They've been a super resource.
Look for a Katie Beckett type waiver or Childrens Medicaid Waiver in your destination state. (Our current state has such a waiver; our destination state does NOT.) Find out how to apply for a waiver if your destination state has one.
Google search Joey Travolta's film camps to see if he's bringing a camp to a university near you. (You guessed it; He comes to a university near me now, but not in our new state.)
Your real estate agent may be able to put you in contact with a support group leader or a parent of a child that is like your child. If your agent doesn't know of any connections, someone in that real estate office might. Be sure to ask.
Even though I am homeschooling, I did google state public education rules and regs as I was looking at homeschooling rules and regs. Some states offer non-core classes to homeschoolers; some states offer special ed services to homeschoolers who qualify. (The state we are departing does both; the state we are moving to does neither.) I also searched for names of schools in our destination city alongside "due process" and other special ed related terms. I turned up one web site by a family in an ugly situation with a school in the area we are going.
My least favorite, least helpful set of resources has come from the professional community. Calling and e-mailing clinics that offer speech, OT, PT, etc., are disappointing. The social worker who answered the phone at the clinic at a huge, well-known university was useless, unable to answer my basic questions about how speech groups are run and how much they cost, and the people who are supposed to know those things never returned my phone call. (Sidebar: The state we are moving to has a law that requires insurance to cover autism-related services up to age 12, and I see a huge black hole of services and interventions for the 12-18 age range, because younger kids are covered by early intervention and insurance, and older kids qualify for medicaid, but the kids in the middle are missed because clinics are going after insurance and medicaid dollars. What a shame.)
If you have moved and have discovered a resource that I haven't included here, please leave your hint/tip in the comments section. I would appreciate more direction as we prepare to head in a new direction.