Consider making spousal RRSP contributions. If you expect your spouse will earn less than you in retirement, contribute to his or her RRSP. The funds must remain in your spouse's RRSP account for a minimum of three years, but when withdrawn they should be taxed at a lower rate. You can claim the deduction immediately for the contribution.
If you withdraw the funds before the three years are up, the amount will be taxable as your income, not that of your spouse.