Risks are rising that Fannie Mae and Freddie Mac may need

Among the nightmares lurking around the corner for the already battered housing and credit markets would be a meltdown at mortgage financing giants Fannie Mae and Freddie Mac.

Although few are predicting an imminent need for a bailout just yet, credit rating agency Standard & Poor's recently placed an estimated price tag on this worst case scenario -- $420 billion to $1.1 trillion of taxpayer's money.