You can play aggresive openings that are also sound. Stuff like the Latvian is risky against a decent opponent while not offering much in return. Think of it like a KG with a tempo down. I don't trust the KG with White, I'm not saying it isn't good, just that there are better moves to try for an advantage, but playing it with a tempo down isn't advisable.

If you want aggresive but sound here is what I would recommend, against 1. e4 the Alekhine or the Pirc, in both lines theory ends very vast and there are plenty of pieces on the board to play for a win, plus many White players don't prepare these openings very well, against 1. d4, Benko gambit. It's the only gambit I can recommand, the second soundest early gambit I can think of is the Morra but that is rather drawish. 

Check out:

As White:

"A Ferocious Chess Repertoire", by Cyrus Lakdawala

As Black:

Versus 1.e4

"Scandinavian: Andersson Counter-attack" by W. John Lutes

Versus 1.d4 Nf6 2.Nf3 try:

"The Nadanian Attack" by Tibor Karolyi (Secrets of Opening Surprises: Volume 5, Chapter 8)

Versus 1.d4 Nf6 2.c4 try:

"The Budapest(Fajarowicz) Can Still Surprise", by Artur Kogan (Secrets of Opening Surprises: Volume 8, Chapter 7)

Versus 1.c4, take a look in the databases at : 1.c4 d5 cxd5 c6!?

Versus 1.Nf3, take a look in the databases at 1.Nf3 h6!?

Versus 1.f4, its gotta be the From Gambit. (numerous sources)

Gamebrain - From's Gambit is aggressive against 1. f4, but maybe not best.  I do pretty well against it, interesting games for sure :-)

 +2

 +2

Kings Gambit is my favorite opening but I play the ruy a lot as well.  Typically I will play the Kings Gambit vs. weaker players and the ruy vs. stronger players.  If I feel like being agressive I will play the KG against anybody.

Well, even if he wasn't the strongest world champion, he was still a world champion. If you mean the opening, it may be unpopular, but white has to be very careful to achieve even a more comfortable position.

The problem with the From gambit from my point of view is that White can immediately transpose to KGs with 2. e4, although he might be just better after accepting the gambit.

I suggested the Alekhine because it's an aggresive choice for Black, putting immediate pressure on White, I admit it's a risky but it's far less theoretical than other openings, and an intermediate level, you'll be out of the book by move ten in any case.

Alekhine said From's is equal, so it is up to White to prove the gambit.  However, there is much less theory, which appeals to me.  

oh, I'm... Sorry...

I just wanted to help.

I'm bad at chess...

Well no! We can't be sad now no way!

 BirdBrain,

The trick to playing the From sucessfully is to dig in to the databases, and look at the lines being played by Black from 1900 to 1960. These lines were fairly virulent, and were never refuted. They just went "out of style" when the newer systems like Nc6 or Nf6 or g5 came along. Black *does* have to have a line prepared just in case White switches to the King's Gambit, but few Bird players, who are positional by nature, will go this route. In my games with the From, I have never had a single opponent transpose to the KG....

what the most aggresive opening you guys recommend?

another Taurus, rising.

GameBrain, I essayed the switch - even bought a KG book by Korchnoi, to study the ideas.  I think a Bird player should know the KG up to a certain point.  Right now, I am convinced that White has no reason not to accept the pawn.  Later in life, with more knowledge, I might change my mind.  Right now, White seems comfortable with a pawn and a position to build.  

There are no aggressive openings if you don't know how to attack.

I agree with Pfren, but I guess Id say the Kings Indian Defense.

For me (not the OP obviously) the reason for moving to more aggressive openings is precisely to develop that skill. I've trying to gear up the courage to dump my opening repertoire and play a strictly gambit based one for a while to force me to learn how to make the most of my pieces and how to attack at all costs. 

OTB I tend to be very materialistic and I also start worrying about losing and go into a passive mode that misses opportuntiies for myself. I'm still winning games (rated 1400'sih and putting in 1700 performances pretty regularly, was 1200 only a few months back), but my losses all have to do with being too passive.

I know that most gambits are less respected than non-gambit lines for a reason, but I'm thinking that if I go into the game down material and my only chance to not lose is to maintain the initiative, I'll learn to do that.

To conduct a successful attack, you need first to develop and position your forces properly. And for that, there is absolutely no need to play an "aggressive opening". You just have to play sane, correct positional chess.

Bah, another nonsensical gambit.

True enough, white might not be really worse after 1.e4 e5 2.Nf3 Nc6 3.Nc3 Nf6 4.Nxe5?! Nxe5 5.d4 Nc6 6.d5 Bb4!? 7.dc6 Nxe4 8.Qd4 Qe7, but he has absolutely no reasons to be cheerful, either. And, of course his position is everything but "aggressive".

There is no fun in the Traxler after 5.Bxf7+ or 5.d4.

Or, if there is any fun, this is on the white side.