GMAC Bank continues to offer top yields on its CDs. Their CD rates have gone down just like everyone else, but they're one of the few with a 4.00% APY on a one year CD as of 12/24/08. Typically, GMAC Bank changes rates on Fridays, so this might not last much longer. The CDs can be opened online, so you should be able to lock into these rates before Friday.
GMAC Bank's FAQ page does a pretty good job describing the CD details. Please refer to my GMAC CD review post for a summary of GMAC's CD features.
GMAC Bank's Online Savings Account continues to offer a 3.75% APY as of 12/24/08. It has no minimum balance requirements and no monthly fees. GMAC Bank continues to be my favorite online bank due to its ACH bank-to-bank transfer features (see my latest OSA review).
GMAC Bank's parent has been in the news lately due to its financial problems. What may happen if GMAC Bank's parent goes bankrupt? Refer to my recent GMAC's troubles post for more on this issue.
GMAC Bank accounts are FDIC insured (FDIC Certificate # 57803).