If so, please give me an example.

not sure probably

...?

ok i just now noticed that lol

http://www.chessgames.com/perl/chessgame?gid=1068106

pipepr: That was a very nice game, but the exchange sacrifice belongs to another category altogether, IMO.... I'm just curious if Karpov ever exchanged an entire piece for a pawn (or two).

 The reason why I'm asking is that I've seen a documentary about Karpov in which his childhood coach claimed that the little Anatoly would never sacrifice even a single pawn for initiative.

Here is an example http://www.chessgames.com/perl/chessgame?gid=1068276

Flav787: Thanks....

Dunno if you're looking for something like this, but he offers a knight on move 21 because he's attacking... his opponent doesn't take it though.

Some sort of vague lasting initiative?  I'm sure there are games out there, this is just the first one I came across.

waffle: An excellent game, but it was't a true piece sacrifice, because if Black took that knight, he'd be mated very soon.

It was a true sacrifice. It simply was not a positional sacrifice, but an absolute one.

chessigoood: A mating sacrifice is not a true sacrifice, because the opponent gets into a mating pattern... A true sacrifice is that for position or initiative...  I'm interested in sacrificing pieces for initiative...

is a true sacrifice an unsound sacrifice?

No, they're different, if you calculate it correctly. An unsound sacrifice is essentially a blunder, due to the lack of calculation. But a positional or initiative sac gives you a fighting chance.

I remember some Shirov ones that really impressed me.  I wish I had saved those games.  Made me feel like a total beginner again... looking at his much smaller army and wondering how the hell he was winning so easily anyway

I'm guessing you're looking for a sac like this... there's no immediate attack, or way to win the material back, but the other guy is miserable and can hardly improve his position.

Yes, something like that. Those type of sacrifices are "unsound" as far as computer evaluation goes, but they're so devilishly complex that the opponent will rack his brains to counter them.  Tal and Shirov are very good examples of that...

You mean his Bh3!! against Topalov?

Actually, with this sac I boarder on chess heresy and entertain the thought that I would have found this move too, because the move makes so much sense to me.

What's likely is I don't understand white's best defense which makes it a brilliant move (because it obviously works in the end) and in my ignorance I think it's an obvious win :)

And it's very likely that in a real game, other moves that only draw would appear much more attractive to me.

When I first saw it I had been looking at some bishop endgames where you sac pawns to for dominating positions.  This is sort of the same thing (dominating king) and so I had the impression that the move was not so immortal :)

No, it's actually a straightforward win -- the difficulty is considering the concept, because it's so striking. I actually played this position (it was a quiz) against a computer, without knowing the solution, and I just played normal moves, completely oblivious to ...Bh3 the entire time. What's funny is that even the computer never suggested the move. If you would have found this move, then you're a great player, because I didn't after taking plenty of time. Of course, it's easier once you have seen something like this before or are very familiar with the concept of doing anything to get a strong king position.