Sacrifice

What is the greatest amount of material sacrificed for a winning positional advantage? It cannot be a tactical sacrifice. No man or computer should be able to see to the point of material gain or checkmate.

I don't know many games, but Waitzkin's double exchange sacrifice is the greatest one I know of sacrificing 4 pawns of material (or was it 3? I can't remember). It seems like there would be much better out there.

Also, could anyone provide games where a queen was sacrificed for a positional advantage?

Anywhere or nowhere.

@ChristianSoldier: I agree that that's a great queen sacrifice, but I definitely classify this as tactical since accepting it leads to mate in 2.

I scraficed 2 knights  for check mate ! :)
and here is the game:

It really all depends on how strictly you define "positional sacrifice". What about this game? Does this count? I mean, it obviously appears to be short and tactical, but White already had overwhelming long-term pressure when a blunder cut the game short. Had Black played differently, it could have gone on much longer but White would most likely have still won eventually.

Serper V nikolidas something or other 1993

Serper Sacs (2 Queens, 2 Bishops, 2 Knights, and 2, Rooks, and nets enough of an advantage to promote 2 Pawns (one of the Queens Saced was promoted to) and wins with an overwelming victory)

Here is the game