A regular investment savings account is a good idea if you have real plans, or at least think that you might, retire early...especially very early. Generally, it's best to max out your tax-advantaged accounts first, but if you plan to screw the man early on and live the life you want to live by your 30s or 40s, then you will need to start planning a stable balance between investment savings accounts and retirement accounts--you want access to your money well before retirement age, and you want to make sure it lasts until you can access the retirement funds--also consider opening up your own private tr or roth IRA (I think you already mentioned this).
When you get comfortable, and especially going into primarily stock-based funds, start looking into funds, like REITs and some others, that offer substantial, regular dividends. These tend to be better for tax-advantaged accounts (because otherwise you would eventually be paying substantial taxes on the accruing dividends each year), but if you pile up enough of them, a lot of people simply live off of dividends, and they are generally impervious to wild market forces, so you usually don't have to worry about income when we have gonzo markets like we do right now (the value of the stock may drop significantly, but the dividends almost always pay out at the same rate. Companies are usually very slow to adjust dividend rates. ...and all companies are different. So research is good. Boggleheads I think has some dedicated dividend people)