Geoboards are something that is great for all ages. As a pre-k (3+ years) child it's a great way to practice those fine motor skills, concentration, shapes, vocabulary and even creativity.
Below is a picture of one of the children creating different shapes and even a picture of herself!
We got ours for only $3.50 on amazon (prime shipping!)
11x11 geoboard on Amazon
Some helpful websites
Pre-kinders: math and geometry
Creek side learning: printable cards for learning shapes