This SmartMoney story compares major cash back card offerings.
I've blogged most of the cards in this web site and my judgments are:
1. Citi Home Rebate Card (No Go) and MBNA GMAC Mortgage Equity Rewards (No Go)
Both cards are no-go. 1% flat cash back is a commonplace offering and you should decide the best use of cash, instead of letting the card issuers help you to decide (same applies to reward cards that reward by gift certificate to certain merchants, see Cashback vs Reward.)
2. College Savings: Citi Upromise (No Go), MBNA Fidelity 529 (Go), MBNA BabyMint (No Go)
MBNA Fidelity 529 is worth a try if you have a kid and want to start 529 saving plan because it offers flat 2% cashback up to a limit of $1,500 per year. (If you already have a Fidelity 529 account it is even better.) Citi Upromise and MBNA BabyMint are inferior because you will have more flexibility asking for cash instead of contribution to 529 plans.
3. BankOne ShareBuilder (Go), MBNA NestEggz.com (No-Go), MBNA Fidelity Investments (Go)
The ShareBuilder card offers 1% flat cashback and credits your ShareBuilder brokerage account when $25 reward has been accumulated. (Because the basic level of ShareBuilder account does not charge maintenance fees, you can just open a ShareBuilder account for this purpose even if you have no intention to invest in the stock market.) MBNA Fidelity Investments is a better choice if you have a Fidelity account -- the card offers 1.5% cash back.
In addition, no matter whether you want to interfere with mortgage, brokerage accounts or 529 plans, you can still consider Citi Dividend Platinum Select, a terrific card that offers 5% cashback on all grocery store, drugstore and gas station purchases, plus 1% cashback on all other purchases, up to an annual limit of $300.
If you have time to research, CardRatings.com keeps a long list of reward card options with brief discussion of each card's unique features.
A final word: be sure to read the fine prints of every program. If you cannot play with the rules, the promised rewards may not be as good as they appears. Read SmartMoney's Just Rewards for common pitfalls.