American Express offers some good cards w/ cash back:

True Earnings Card from Costco and American Express

• $25 statement credit w/ first purchase
• 3% cash back for gasoline, 3% for restaurants, 2% for travel, 1% for everything else
• No limit on cash back you can earn.
• No annual fee
• Also works as Costco membership card

Blue Cash from American Express

• 0% introductory APR for upto 12 months on purchases
• upto 5% cash back on purchase at supermarket, gas stations and drugstores, 1% on everything else.
• No limit on cash back you can earn.
• No annual fee

SimplyCash Business card from American Express

• Earn 5% cash back on office supplies, and wireless services
• Earn 3% cahs back on gas upto $12,000 per year, 1% after
• Earn 1% cash back on virtually all other purchases
• 0% Introductory APR for the first 12 months
• Cash back is automatically credited to the statement each month
• No fee with the flexibility to pay in full or carry a balance