Today is pay day for a lot of people, so here are some sites that help find good deals on stuff to buy on the Internet. First I tried to find places that had deals specifically for children (which there weren't that many of), so I've linked to those first.
Baby and Toys categories at Cheap Stingy Bastard
Babies & Kids and Toys categories at Fat Wallet.com
Baby & Kids and Toys categories at dealcatcher.com
Baby coupon and bargains at amazing-bargains.com
Not a lot of kid stuff, but still plenty of deals for dads:
Post more in the comments if I've missed any you frequent.