Crow's feet can be partially prevented through the consistent use of sunblock. Some cosmetic dermatologists now advocate the preemptive use of Botox or other injectable wrinkle reducers around the eyes to prevent the formation of crow's feet (among other wrinkles).
Crow's feet can also be caused by squinting excessively, so wear sunglasses when in bright light and make sure your vision prescription is up to date. And don't smoke - it's terrible for skin.
Product treatments: Moisturizers and concealers can temporarily mask the condition, and baby crow's feet may be reduced by the use of retinoids (like Retin-A).