I've been giving my six year-old with PDD-NOS fish oil since he was 18 months old.  We switched to a new brand in December 2009, and in mid-January 2010----my son finally started talking.  I'm not sure if it was the new fish oil or not, but I'm continuing to give it to him.  His speech has been improving tremendously over the past few months.  The fish oil is called:  Barlean's Total Omega 3-6-9.  (I bought this one b/c I had read good things about the combination of omega 3-6-9's working together.)  I bought it in the health food section at Market Street for about $30 for a big bottle.  I give my son 3/4 of a tsp each day with a medicine syringe.  It has a lemon flavor.  He's not crazy about it, but takes it each day.  I'm not sure if it will work for you, but it might be worth trying for a few months. 

:) Heather