Winning combinations in the Fischer/Sozin/Velimirovic Sicilian(s)
Rule of thumb: if Black can play in a normal Sicilian *) d6-d5, he is usually on top. Very often White's position collapses afer d6-d5 in a few moves.
Here's a rather easy, but convincing example:
*) Both the Dragon and the Sveshnikov are not normal and have their own rules of thumb (In this case, this 'd5-rule' also applies for the non-normal Sicilians)