I too would put Derrida in a different category, that of linguistics. But his thinking does greatly impact philosophy for those who allow him too. His first two major works basically deconstruct what we know, he orginated the concept of binary opposites, and has taken culture on a major turn-- one that only seems to appear about every 500 years. But Derrida owes much to Wittgenstein, Sassure, & Focault at his roots. If you take Chomsky at only his "generative linguistics" work, then he too can be considered a "philosopher" in my opinion.
Again, as I said before, the lines between philosophy / politics / liguistics / science / religion are now greatly blurred in a way they were not even 30 or 40 years ago.
No no no no no no no Oh God No!
Sorry, but seriously here - you're wrong.
First off because Derrida really isn't a linguist as far as linguistics is done today - he's firmly in the Philosophy of Language. (Bear in mind, he seems to display a profound semantical skepticism, and to write mostly about that. That isn't immediately a problem - many other philosophers do too. Semantics is a very tricky problem. )
Secondly, he invented the notion of binary opposites?
Um, I hope you meant something other than the literal meaning of this, because come on...
Thirdly, HAH! Derrida did create a small move, interesting mostly in the sociological aspects, among certain of the Humanities (though, importantly, not in the one he seems to be writing - this is always something to watch for, it tends to indicate the presence of a flamboyant and dramatic but not particularly profound or interesting writer). He hardly brought about any profound changes otherwise, though. Compared to the American Pragmatists (early and later); the Young Hegelians; the early Analytic movement; etc. his massive changes are pretty puny. And none of the above were the sort of massive changes that only happen every 500 years either.
Fourthly: Chomsky has actually written a decent amount of (well, not too great) Philosophy - usually within the mental representation debate. I certainly don't agree with him or think him particularly good at doing it, but he's certainly had more philosophic influence that just Generative Linguistics.
Finally the lines between all those catagories above have
always been deeply muddled. Partially because all of them are the subject matter of philosophy, as well as being interesting subjects in themselves, and partially because that's just how things are when it comes to intellectual inquiry. The largest change in the last couple decades/centuries has been towards specialization, and not the other way around.