sharp responds to 1.d4?

here is my personal favourite from the modern defence. post others you know :)

I like the Benko gambit.

Some good choices are: Semi-Slav, Leningrad Dutch, Benko Gambit, Blumenfeld Gambit, King's Indian Defence, Modern Benoni, and the Grunfeld.

My favourite to analyze is probably the Semi-Slav, especially after white plays 5.Bg5. Unfortunately, white can make the game boring if he avoids it or the Meran variation, often with the exchange Slav or 6.Qc2 without 7.g4. The Leningrad dutch is probably the best choice if you need to fight for a win at all costs, as there aren't really any forced drawing lines or exchange variations.

I play the Leningrad Dutch sometimes.  I always feel like I'm hanging by a thread, even in the games that I win with it.  It does lead to sharp, out of the ordinary positions that are fun to play.

i vote benko.

@Fiveofswords: I was just about to mention those two along with the Chigorin Defense. I personally don't see how you can call anything else sharp without having those three in the discussion.

There are people who like those gambits; what to recommend in my opinion depends on white's rating.

1...g5!

Either the Modern Benoni, Leningrad Dutch, KID are good choices. The Semi-Slav is also sharp if white plays the Botvinnik variation or Meran variation but white can just play the 6. Qc2 sideline and avoid both. Even in the Modern Benoni, white can play Nf3 instead of d5 after you play c5 and transpose into a quiet variation of the English opening. Like BigTy said, playing the Leningrad Dutch is a good way to ensure an unbalanced, sharp game.

d4 seems to be less aggressive than e4.  why so?

it's easy to use budapest gambit when white use d4.

Benko Gambit, Modern Benoni, Dutch Stonewall, QGD Noteboom and QGD Semi-Slav especially if white answers 5.Bg5.

Easy, sure, but why would you want to?

I enjoy the Nimzovitch defense, it gives many opportunities. Here are the main ideas of this opening (on black side) :

That is not the Nimzowitsch Defence (1. e4 Nc6), but the Nimzo-Indian Defence.

i think benko gambit is the worlds sharpest lines in d4 .

Benko gambit  prefer  :)

Benoni :)

I like the Nimzo Indian, though I play it very rarely. May be not at all!

Modern Benoni, no wussy drawing lines for white to play.