If the IRS is sending you a big tax return this year it means that you had too much withheld from your paycheck during 2007. I know that many of you consider your tax return to be a forced savings account, so let's take that idea one step further. Considering you can afford to live without the money the IRS has been holding for you all year, why not direct that exact amount toward your retirement account?
Revise your W-4 so that you're having the correct amount of taxes withheld, and then average the amount of your tax return over 12 months. Increase your 401(k) contribution by this amount each month — you won't miss the extra money from your paycheck since it hadn't been going to your bank account anyway, and your future self will thank you. Already contributing up to the amount your employer matches in your 401(k)? Set up automatic deductions from your bank account to your IRA or savings account instead.