In Just Cause 2 theres a weapon thats basically a modified jet engine styled into an 'under the arm' bazooka.
It acts as an eff off big hoover that can be used to blow people sky high - at short range it can even turn cars over. Great to stand at the side of the freeway and ruin peoples day! The physics of it are spot on (as you'd expect from JC2) It mullers anything in its way!
What are the most memorable gaming weapons for you?