If you live in the United States, and your child is under the age of 3 years (36 months), you can get help from your state Early Intervention Program. That help is typically in the form of evaluations and therapy. Please see my FAQ section for more info.
This list is updated as of Feb 2010:
Alabama: http://www.rehab.state.al.us/Home/default.aspx?url=/Home/Services/AEIS/Main
Alaska: http://health.hss.state.ak.us/ocs/InfantLearning/default.htm
Arizona: https://www.azdes.gov/AZEip/
Arkansas: http://www.arkansas.gov/dhs/ddds/FirstConn/index.html
California: http://www.dds.ca.gov/EarlyStart.home.cfm is the main site. It hasn't been working. Try:
http://www.php.com/services/early-intervention-infants-toddlers-0-3
Colorado: http://www.eicolorado.org/
Connecticut: http://www.birth23.org/
Delaware: http://www.dhss.delaware.gov/dhss/dms/epqc/birth3/directry.html
DC: http://www.osse.dc.gov/seo/cwp/view,a,1224,q,562131.asp
Florida: http://www.cms-kids.com/families/early_steps/early_steps.html
Georgia: http://health.state.ga.us/programs/bcw/index.asp
Hawaii: http://hawaii.gov/health/family-child-health/family-child-health/eis/index.html
Idaho: http://healthandwelfare.idaho.gov/default.aspx?TabId=78
Illinois: http://www.dhs.state.il.us/page.aspx?item=32009
Indiana: http://www.in.gov/fssa/ddrs/2633.htm
Iowa: http://www.earlyaccessiowa.org/
Kansas: http://kdheks.gov/cds/index.html
Kentucky: http://chfs.ky.gov/dph/firststeps.htm
Louisiana: http://www.dhh.louisiana.gov
/offices/?ID=334
Maine: http://www.maine.gov/education/speced/cds/index.html
Maryland: http://ei.mdecgateway.org/earlyinterventionsystem
Massachusetts: http://www.eiplp.org/
Michigan: http://www.1800earlyon.org/
Minnesota: http://www.health.state.mn.us/divs/fh/mcshn/directory/
Mississippi: http://www.msdh.state.ms.us/msdhsite/index.cfm/41,0,74,html
Missouri: http://dese.mo.gov/divspeced/FirstSteps/index.html
Montana: http://www.dphhs.mt.gov/dsd/homebasedservicestofamilies/earlyinterventionservices.shtml
Nebraska: http://edn.ne.gov/
Nevada: http://health.nv.gov/BEIS.htm
New Hampshire: http://www.dhhs.nh.gov/DHHS/BDS/family-early-support.htm
New Jersey: http://nj.gov/health/fhs/eis/index.shtml
New Mexico: http://www.nmhealth.org/ddsd/NMFIT/FITIndex.htm
New York: http://www.health.state.ny.us/community/infants_children/early_intervention/
North Carolina: http://www.ncei.org/ei/itp.html
North Dakota: http://www.nd.gov/dhs/services/disabilities/earlyintervention/parent-info/right-track.html
Ohio: http://www.ohiohelpmegrow.org
Oklahoma: http://sde.state.ok.us/Curriculum/SpecEd/SoonerStart.html
Oregon: http://www.ode.state.or.us/search/results/?id=252
Pennsylvania: http://www.dpw.state.pa.us/About/OCDEL/003676718.htm
Rhode Island: http://www.dhs.ri.gov/ChildrenwithSpecialNeeds/EarlyInterventionProgram/tabid/839/Default.aspx
South Carolina: http://www.scfirststeps.org/babynet.html
South Dakota: http://doe.sd.gov/oess/Birthto3/index.asp
Tennessee: http://www.tn.gov/education/teis/
Texas: http://www.dars.state.tx.us/ecis/index.shtml
Utah: http://www.utahbabywatch.org/
Vermont: http://dcf.vermont.gov/cdd/cis/IDEA_Part_C_early_intervention
Virginia: http://www.infantva.org/
Washington: http://www.dshs.wa.gov/iteip/
West Virginia: http://www.wvdhhr.org/birth23/
Wisconsin: http://dhs.wisconsin.gov/bdds/birthto3/
Wyoming: http://wdh.state.wy.us/ddd/earlychildhood/index.html