buying treasuries is the safest (or you can buy a money market fund that invests solely in them). next safest would be EFP's.
Consider opening savings accounts at different banks (online or otherwise) making sure that the amounts don't exceed the FDIC limits. http://www.fdic.gov/deposit/deposits/insured/ownership3.html You may also want to consider CDARS which help to bypass the FDIC limits. http://www.cdars.com/index.php All these being a temporary staging area for at least some time...