Roth IRA for $3K at Vanguard and their VFINX S&P 500 stock index mutual fund is a good retirement investment.
You don't get a tax deduction with a Roth IRA, but all growth in value is tax-free. You can set up a Roth IRA as long as you have earned income above the amount you're putting in, and you can do it even if you have a 401k plan at work.
www.fool.com has good articles on investing, and an Advanced Search of archived threads ("invest", "broker") will turn up some good threads on investing.