Absolutely. I’d have to say emphatically that if one had credit card debt or loans where the interest rate exceeded that of CDs, and if one did not use that money to pay off that debt, then future monetary woes are as inevitable as the sun rising in the east. And believe me, I know a family who lived paycheck to paycheck, ran each card up to the limit, and blew a large insurance settlement on nothing at all. They’re back to where they started, and with absolutely nothing to show for it. I think that mortgages are a bit different; if you can handle the monthly payment, it allows you to itemize deductions for other things, so it almost pays for itself and I wouldn’t make it a priority.
For those parents out there: I can’t believe what college tuition costs these days. You’d be wise to think of stashing that money away for that.
With no children, think of contributing the maximum to your employer 401K. If it hurts to do that, then you could use a corresponding amount of money from the 50G for living expenses. Again, the tax benefits from contributing to the 401K will help at the end of the year.
Even with the housing bubble having burst, your home is still your home. If you need a new kitchen or bath or addition, then you need it. Don’t have it built hoping to make a bundle when you sell, but rather for your own enjoyment. Nevertheless, it seems like a reasonable use of the money to me. And if you don’t have a home and want one, a down payment would be an excellent use for this money. Just spend some time, and get to know the market.
Assuming that the 50G was after taxes: I have no outstanding debts, no children, and I max out on my 401K. I’d make the maximum contribution to a Roth IRA. After that, I’d use some money for some home improvement projects that I can’t do myself, although there isn’t much that I need done. I’d consider either putting the remainder in mutual funds, or else in an interest account and using the interest to fund a mutual fund.
I don’t think that any of this will appeal to anyone under 50. 
And on preview: Wow, what a lot of response while I was composing this! Nice to see the focus on debt.