Technically not a blog, but I am a fan of a Facebook page called "Serious Super Savers" fanpage.
I recommend using coupons with those grocery store cards for items on sale.
Coupon + Store Savings Card + Sale item = Biggest Savings
It requires a bit of organization and planning, but with a family of 5 we save literally hundreds on groceries a month.
Websites like cellfire[dot]com will allow you to print off coupons and even put electronic coupons on your store savings card so you don't need a coupon when you shop. Upromise[dot]com lets you save when you buy all kinds of things.
If you just do the above things, you will easily save more than $100 this month.
Hope this helps.