I'll be 30 next week. I want aggressive funds and can tolerate risk at this state in the game as I need to see good returns to get where I want to be, when I want to be there.
I am far, far, far from anything resembling an expert, but I'm getting a little closer each day. I enjoy getting others opinions with sound reasoning and seeing what they recommend or what they would do in my shoes.
So considering that this is money you will not be touching for at least another 20 to 30 years, and you are willing to take a lot of risk, I would stay away from index funds and go with managed funds. However, I would diversify widely because good managers can have bad years and even bad streaks. Examples of this are Bill Miller of Legg Mason Value Trust and Bruce Berkowitz.
You should diversify in two ways, by fund company (Fidelity, Vanguard, American, Dreyfus, Putnam, etc.) and by type of fund (US large cap stock, global bond, foreign small cap value, etc.) because it has been shown that different type of funds from the same company many times have the same holdings. This happens because the managers at a fund family may be bullish on a particular company, so that company could appear in several different funds of that family.
It will also help that you are adding to the portfolio each month or quarterly because you will be in a sense "dollar cost averaging" and not buying all at once, possibly at the worst time.
And another thing, don't allow your age keep you away from bond funds. They can be a good cushion when the stock market is having bad times and are an important component of a well-balanced portfolio. You should have a minimum of three or four bond funds of different types, not just one.