General shopping sites:

Here are some of the more popular general/misc. shopping sites:

Amazon
Bed Bath and Beyond
BJs
Cabelas
eBay
Home Depot
Lowes
REI
Walmart

Office supplies, computer, shipping, etc.

Here are some of the more popular office supplies, computer and shipping companies:

Adorama
Best Buy
Dell
FedEx
Newegg
Quill
Staples
UPS
Verizon Wireless

Travel & Transportation

Here are some of the more popular travel and transportation companies:

Car rental:

Avis
Budget
Dollar
Expedia
Orbitz
Priceline
Thrifty
Travelocity

Airlines:

Expedia
JetBlue
Orbitz
Priceline
Travelocity

Other/various:

Hotels.com
Orbitz
otel.com
Priceline
Travelocity

Shopping for supplies

Adorama
Amazon
Avast
Avis
Budget
Bed Bath and Beyond
Best Buy
BJs
BlueHost
Cabelas
Dell
Dollar
eBay
Expedia
FedEx
Fandango
Home Depot
HostGator
Hotels.com
Groupon
iTunes
JetBlue
Lowes
Newegg
Orbitz
otel.com
Priceline
Quill
QuickBooks / Intuit
REI
Staples
Ticketsnow
Travelocity
UPS
Verizon Wireless
Walmart