If you are looking for a zero risk savings vehicle for the money you set aside as savings that offers the highest interest rates available you'll want to look at online banks. Online banks are able to offer such high interest rates because they have little overhead costs with no physical bank branches and a usually small staff. These savings are passed on to you the consumer as interest rates that are far higher then traditional savings accounts at traditional banks.
ING Direct is a leader in the online savings and banking industry and their simplicity combined with high interest rates makes for a great account. They have zero fees and no minimum balance. They are also fully insured and a well recognized brand around the world. You can easily set up an account with them in minutes online and even set automatic deductions direct from your checking account to build your savings. If a free savings account wasn't great enough, ING Direct's interest rates paid to you on your savings are currently in the 4-5% range while a traditional bank savings account will net you about 0.45% interest on your account.
ING is clearly the easiest and wisest choice although shopping around you'll see other companies such as E Trade Financial (known for low cost stock trading) offering free online savings as well with interest rates around those of ING Direct. Even traditional banks are beginning to offer online savings but their interest rates tend to be lower then those of ING Direct and similar online only banks.
Overall ING is best however if you choose to look for high yield interest savings accounts without the risk of stocks and investing, just be sure that the bank you choose is FDIC insured and do not settle for any account charging fees, offering sub-par rates, or places absurd restrictions (such as account maturity) on accessing your hard earned money.