Keep cats away from Easter Lilies and other Asiatic Lilies as cats can suffer acute kidney failure within a very short period of time from just a licking a few pollen grains off their fur.
See more about Lilies and Cats at:
Read more about Cat-Friendly Gardening here:
Here is a List of SAFE Plants for Cats:
Photo Source: FDA
(This is an updated blog post from Spring 2014)