If it is out there, somebody somewhere is allergic to it. So no, there is no cat no one is allergic to. But as mentioned before, there are some people have luck with. People say the Rex varities are good, and also Siberian cats. I don't know about the Rex cats, but Siberians have less of the protien that causes dander. If people are truly less allergic to Rexes, it would be for the same reason. Do no imagine that because a cat has less hair, it will be less allergenic. You are allergic to the dander, not the hair.
At the University of Colorado (I'm pretty sure) there is a couple starting a highly controversial experiment to try to make non-allergenic cats through gene-alteration. This is controversial for several reasons. First, they do not know if it will work. Second, they do not know how it will change the cat, healthwise and otherwise. Third, they will need to make lots and lots of new cats, which will need to be homed or killed eventually, even if the experiment does not work. Fourth, the potentially non-allergenic cats will not be available until at least 2003, and then cost between $750 and $1000.