Ideal investments for tax deferred and tax advantaged accounts: Taxable bonds, commodity funds, REITS (Real Estate Investment Trusts), Individual TIPs (Treasury Inflation Protected Bonds), and individual stocks that pay a large dividend. These investments may face unfavorable tax treatment in a taxable account and therefore are better suited for tax advantaged accounts. If you actively trade stocks (not recommended) it may be beneficial to do so in an IRA to avoid short-term capital gains, which are taxed at ordinary income tax rates.
Ideal investments for taxable accounts: Individual stocks that pay no dividend, or a small dividend, index stock funds and ETFs, tax managed funds, and any tax-free investments such as municipal bonds and funds.
Ideally you would want to hold taxable account assets for longer than 1 year to be eligible for long term capital gains treatment. Investment assets eligible for long term capital gains or are tax-free should be held in taxable accounts.
The details may seem trivial, but where an asset is placed can make a significant difference in the net amount your investments are worth. Paying fewer taxes and allowing years of compounding to work in your favor can really increase your net investment returns.