This thread has concentrated mostly on contributing to retirement plans to help reduce taxes, but there are a few other methods to consider as well.
Foremost, don't forget to use tax software. The questions will help prompt you for deductions.
There's not a whole lot outside of contributing to a 401(k) plan to reduce W2 wages, but there's a lot one can do with investment income.
1. Try to get all your investment income in a tax-free (Roth IRA) or tax-deferred (401(k) or traditional IRA) account. All income in a taxable account should at least be qualified dividend income and get you a more favorable tax rate. You don't want to hold a REIT fund in your taxable account, but such a fund would be great in your 401(k) or IRA instead.
2. Try not to realize capital gains. There are no taxes owed on unrealized capital gains. If you must realize gains, try to make sure they are long-term and taxed at a more favorable rate or sell your losers to offset the gains.
3. Sell your losers while they are still short-term (held less than a year), especially in Nov-Dec of each year. You can use up to $3000 in excess losses to offset ordinary income and carry forward to next year losses larger than that.
If need be, you can do some swaps, like sell LOW and buy HD, if you wish to remain fully invested (as you should).
4. Use all the itemized deductions you are allowed. This means give money to charity, pay your property taxes, pay your state income taxes or sales taxes, pay your mortgage interest. Deduct them all. If you don't have enough to itemize, consider bunching deductions into one year. That is, donate to charity in Jan 2007 and in Dec 2007. Pay your property taxes in Jan 2007 and Dec 2007. Then itemize every other year and take the standard deduction in the other years.
5. Got young kids and both parents work? Take the dependent care credit. Summer day camps qualify. Sports camps qualify. I am told your maid service qualifies as well.
6. There are few more esoteric tax savings. If you are blind you get an extra allowance, so you can poke your eyes out. You can deduct medical expenses that exceed 7.5% of your AGI, so to save taxes you can get really, really sick.
7. Pay a lot of money for investment advice. If you pay more than 2% of your AGI, then it's deductible. Of course, why anyone would want to pay so much for advice is beyond, but you wanted ideas for saving on taxes and not on having more money in your pocket.