For me it was the 2E Skills and Powers. This was the min/maxer's dream come true. It had rules for splitting your stats into two categories each. Basically your stat was split into the bonuses and then the stuff you didn't care about. Then you could take from one to give to the other. Lots of min/max rules in there. It had nothing of any substance, just ways to try and squeeze out a bonus here and there by sacrificing thing that had no mechanical advantage.