IIRC the PS2's dual shock 2 had pressure sensitive buttons. It wasn't a feature used by a lot of games. Nowadays only the shoulder triggers are analog I think.
It's a shame, really. For example, Metal Gear Solid 2 used this to great effect. If I recall correctly pressing square on the control would raise your weapon but not automatically fire it until you actuated the button all the way? It was finicky, but very cool.
I hated how they worked. The buttons did not have enough travel in them to be comfortable to use in this way plus the way the thumb sits on the buttons it is not a very comfortable way to control pressure like with your fingers on the shoulder triggers. I am glad the Dual Shock 4 got rid of them and just has two decent shoulder triggers.
For automatic weapons, yes, but it was even neater for handguns. Square raised the weapon, releasing quickly fired, easing off slowly eased the hammer back. It was a really neat trick.
I always thought more games should have used the gamecube shoulder buttons' feature. Analog and then a click before the bottom which allows it to be used for subtle followed by accurate/sudden actions. I can only think of two games that used it... Mario Sunshine (button was probably included just for it) and Eternal Darkness. Does anyone recall if a shooter did this for aiming on gamecube? I didn't play many shooters on there.
ps3 does too. on GT5 amount of pressure controls amount of throttle.