Heres a few transaction scenarios for you, you can also check out the walgreens thread for more great ideas.

Transaction #1: Feminine Care
Sale: U by Kotex Feminine Care 14 to 18 pack Maxi Pads, 50- 60 pack Pantiliners, 18 pack tampons. $3.49
Buy: 1 pk U by Kotex
Use: $1/1 Printable coupon HERE
Pay: $2.49 + Tax
Get: $2.50 Register Reward

Transaction #2: Dental Care
Sale: Oral-B Crossaction Pro-Health Toothbrush; Crest Pro-Health Toothpaste, 4.2 oz., Glide floss, 38.3 to 55 yds. 3/$9
Buy: 3x Oral-B Crossaction Pro-Health Toothbrush
Use: Oral-B Pulsar, CrossAction, Advantage, any $2/1 or any (2) Indicator Manual Toothbrushes (4-30-10) PG-4/4
Use Register Rewards: $2.50 from Transaction #1
Pay: $0.50 +tax
Get: $3.00 register Reward

Transaction #3: Hair Care
Sale: Garnier Fructis Hair Care, Shampoo or Conditioner, 10.2 or 13 oz., Styling Products 2 to 8.5 oz. 3/$10
Buy: 6x Garnier Fructis Hair Care, Shampoo Conditioner or Styler.
Use: There aren’t any Insert or Printable coupons, but many times if you ask they have some tear pads stuck behind the cosmetics counter.
Use Register Rewards: $3.00 From Transaction #2
Pay: $17.00
Get: $10 register Reward

There are also coupons to go with the Toothpaste and Floss:
Crest Toothpaste 4.0 oz or larger or Liquid Gel .75/1 (4-30-10) PG-3/7
Glide floss 35M or more or Glide Picks 20 ct or more .75/1 (4-30-10) PG-4/4
They don’t end up being free, but still a great price if you need these items.

Other Great Deals:
Pilot Erasable Frixion 3 pack Highlighters, 2 pack Gel Pens Sale: $1.19
Use Store Coupon: Pilot Frixion Yellow Highlighter, 3 pack or Black Gel Pen, 2 pack $1/1. In the Monthly coupon pamphlet.
Pay: $0.19 +tax

If you have any questions about how Register Rewards work go here for the answers.