Online Stores and Rewards Programs

Amazon.com - Books, CDs, you name it
Costco
ThinkGeek - Stuff for Smart Masses
Adorama - Cameras, etc
Best Buy
Clinique - Makeup & more
1-800-FLOWERS - online flower orders
REI - Outdoor gear
Checks Unlimited - from Current
Jacquie Lawson - Electronic greeting cards
Dick's Sporting Goods (MyScoreCard)
Office Depot

Clothing

Zappos.com - Shoes
Overstocks.com - "The excess supply website"
Lands' End - "Casual clothing company"
L.L. Bean - "Outdoor specialties since 1912"
Coldwater Creek - "Women's apparel, accessories & gifts"
Nordstrom - "Shop from over 400 brands"
The Gap - more clothes

Books (including rare and out-of-print)

Osprey Publishing - Military history books
abebooks.com - Large source of out-of-print books
Bibliofind - Another source of rare and used books

Shopping Guides

Consumer Reports - Official site
Edmund's Automobile Buyer's Guide - Detailed info on car makes, pricing, rebates, holdbacks, etc.