The principles and parameters paradigm says that most languages in the world have their individual structure (grammatical meta-rules) set (and easily learnable) by a small set of principles and parameters. For example, English is (mostly) right-branching (modifiers come -after/o the right) of the modified head) and non-pro-drop (it must have pronouns with the verb).
Is there a reference list somewhere of which languages have what value of the parameters? WALS has an unbelievably long list of features, but frankly none of them correspond to the more abstract theorized parameters.
Also, implicit in this question is what are the currently accepted parameters. The wikipedia article has a list of including head and pro-drop, but there seems to be lot of overlap among those given, showing that that list may not be totally coherent (or equally may be a reflection of the lack of coherence of the research so far).