Here's what my family of five regularly buys:
food
cereal (whatever is on sale, esp. Cheerios)
2 lb blocks of cheese
bacon (4 lb Kirkland)
bread (2 pack white for kid sandwiches)
peanut butter
canned beans (black, garbanzo, refried)
seaweed (individual snack packs)
bagels (Einsteins 2 pack)
whatever snack is on sale that month (goldfish, crackers, cereal bars etc.)
applesauce
coffee
yogurt
household
vitamins
shampoo (whatever is on sale)
cat litter
toothpaste
Kirkland brand toilet paper
butt wipes (ahem, a "splurge" for wiping the youngsters)
Tide
Finish dishwasher tabs (break in half, get two washes out of each one)
breathing strips (a snorer amongst us)
Kirkland brand Claritin
sunscreen
lotion
For all of the household, we wait for the rotating sales and most of the food as well. Sometimes I try new frozen or fresh products on the sales. We also buy socks, shoes and clothes when they are a good deal, some toys at Christmas.
What we don't buy
Beer (bad selection, IMO)
milk (worst jug design ever)
carrots and other bulk veggies (can't finish them in time and not cheaper than grocery store)
diapers (cheaper at Target)
chips (gargantuan bags that encourage binge eating)
hummus (great price but too big and we often had to throw away some)
eggs (too many at once)
quinoa (used to buy, but every time I made it it tasted like ass. What am I doing wrong? I love the taste of other peoples' quinoa)
Thanks for the tip about LEDs. As our CFLs and incandescents die, I will replace them.