The Stay-at-Home-Mom Survival Guide: Preschool Activities This is a GREAT site. She has so many clever and easy ways to work with your preschooler and have fun at the same time. They also have infant and toddler activities.
71 Things You Child Needs to Know Before Kindergarten
Some ideas of things to work on in pre-school. "Parents can learn how to educate their pre-K children through “montessori at home” youtube videos, and library books, and Kumon work books for ages 2-5, and getting play dough or clay for them and beads for stringing, and markers and paper, and reading and counting with them, and doing puzzles and talking about shapes and sizes and locations"