There are several places online to find coupons in addition to getting your weekly paper.

Coupons.com
SmartSource.com
RedPlum.com
eBay

eBay is a great way to buy items in bulk when they are cheap.

For Kroger specific
CellFire.com
ShortCuts.com
P&G eSaver

Get a subscription for All You Magazine. There are tons of coupons each month in the magazine, not to mention great cheap recipes.