There are several good options that are easy to set up and cheap to maintain, including the Simple IRA, Simplified Employee Pension IRA (SEP-IRA) and Solo 401(k).

These three plans all offer tax-deductible contributions, and money inside the plans grows tax-free until you take it out. But there are key differences -- most significantly, how much money you can put in and what happens if you add staff.

Heres's an article that talks about the basics.