Math Websites and Books

(Explanations are quotes - I haven't checked these out for myself yet)

Livingmath.net Peruse Julie Brennan's extensive book lists. Her site is outstanding.
www.hoagiesgifted.org/mathematics.htm - Sir Cumfrence books. Q is for Quark and G is for Googol are good for older kids

Greg Tang books - They're not traditional math books -- more like problem solving with
numbers. For my mathy kid, they were great because they reinforced his
inherent 'number sense' and were fun and visually-attractive. Tang's books aren't really instructional books, though. More like recess with math
especially try Math For All Seasons.