Put on your nostalgia goggles people, let's reminisce for a while...
Clayfighter 64 - bizzare clay figurines filmed in stop motion instead of CG models, a parody of ludicrously violent fighting games at the time. People say it's bad for some reason, but I don't remember it being anything other than outrageously fun. "Get ready to crumble!" Tied with JFC for the scariest game I ever played on N64 (The main menu music was disturbing enough!)
Jet Force Gemini - a couple of space cops, their cybernetically enhanced dog (who has a jetpack and tank armor strapped to him), and a sentient RC helicopter take on a legion of nazi space ants, who have initiated a war of extermination against a peaceful race of tribal teddy bears. Awesomeness ensues. This was also my first exposure to the idea of "the holocaust", and you get to see it first hand. Holy crap is this a scary game, especially Mizar (aka, gigantic praying-mantis Hitler)! After seeing first hand the atrocities these guys committed, it felt so darn good to blow the ant-goons into a gazillion pieces with your rocket-handgun.