Start an INGDirect.com savings account if you don't have one already. Add money to it all year.
Once a year, take enough out to fund a Roth IRA contribution for the previous year (deadline for 2004 is 4-15-05). As usual I'll recommend opening the Roth IRA account at vanguard.com and putting the money into their VFINX mutual fund (S&P 500 index fund).