US Treasury Bonds - These are considered the top-of-the-line bond investments. They are the lowest risk bonds, which means that the coupon rates are also going to be low; and if demand for them is high they might be overpriced.
High Quality Corporate Bonds - These have higher coupon rates than US Treasuries. There is more risk to them because a company can go into bankruptcy, though this is considered less likely with the highest rated ones.
Dividend Stocks - Again, quality is the watchword. Companies with a history of strong earnings, and regular dividend distributions are something to be sought out.
Tax-Exempt Bonds - These are issued by states, counties, and municipalities. The tax-exempt feature has always made these attractive investments to investors because the after-tax return adjusted for the investor's tax rate is actually higher than the coupon rate on the face of the bond. Any tax-exempts, including municipal bond funds, are considered a low risk investment, and the low coupon rates for the bonds reflect that. During deflationary periods they would still look good to many investors.
Bank Certificates Of Deposit (CD) - A CD offers a good short-term alternative for deflationary investing when interest rates are low. They can be considered risk-free because they are insured by the Federal Deposit Insurance Corporation (FDIC) up to whatever the limit happens to be.