How about good old American Treasury Bonds? 100% safe, guaranteed return on investment. Take the I-Bond (Inflation Indexed bond). It currently yield 6.73% (readjusts every 6 months). 1 year ago it yielded 4.6% (at the same time money markets were at like 2%. The interest grows tax deferred, and is exempt from state taxes (which makes the effective yield something lik 7.4% here in Oregon).
4-5 years ago they were yielding north of 9%.
www.treasurydirect.gov
(they have a 30k max per year investment, and a minimum 1 year holding period).
Thus far I can't find any reason anyone would ever choose a CD or bond yielding less then 5% when this option exists.