SWVXX - it's just too easy a task to buy 'INSURED' deposit instruments (such as CD's) than to assume any risk with all of the redundant 'non-insured' boilerplate on these money-market-funds, imo?
Each to his own risk tolerance, but I'm guessing nelson, michael t and jtomm had some very sweaty palms back when Lehman went tits up...