Exchange Sacrifice

I've heard that Tigran Petrosian developed the theory of the positional exchange sacrifice. Here's an exchange sacrifice by Petrosian that I think is in-between purely positional and tactical:
Petrosian - Estrin Moscow 1968
What I like about this game is that it seems the exchange sacrifice wins immediately but a series of semi-quiet moves follow the exchange sacrifice which leads to a dominating position for White. Another point about this game is that I play a similar opening with White and have some hope of pulling off something similar in my own games!
Here's another game I'm very impressed with although it's not strictly an exchange sacrifice game. The idea of surrendering material to recompose a damaged pawn structure is not something I've seen before:
Anand - Wang Hao Wijk Aan Zee 2011
This game was covered quite well by Daniel King and KingsCrusher on YouTube. Search for Anand Wang Hao on YouTube to find the videos.