An Installment Certificate is a security (not backed by the FDIC)that's exclusive to American Express (I didn't realize this when I posted my question.) It has similar features of a CD, but it allows you to save monthly and earn competitive yields that will be better than CD's over time with the bonuses.

Rates are tied to an average rate of money market accounts,guaranteeing that rates will be within a range from 0 to 100 basis points above this average. Interest is compounded and credited at the end of each month, and if the bonus criteria is met you can earn an addtiional 5-20%.

Installment certificates invest largely in bonds, and after reading the prospectus about 10% of investments are rated below investment grade.

I was just wondering if anyone's has ever utilized these certificates or could see reason to avoid them.

Here's a link a prospectus I found, other than this information seems limited:
http://finance.americanexpress.com/sif/cda/page/0,1641,2688,00.asp