Personally I think Jodie Foster in her childhood films takes a lot of beating, but there are some very good others out there who made it beyond acting as children into acting as adults.

oops just put on like this just now sorry, didnt see yours, Id say Mickey Rooney and Shirley Temple, has to be two fantastic talents of all time.

i'd have to say Dakota (or is it Dekota, i'm not sure) anyway Dakota Fanning, but thats from watching Taken, years ago.