I’d pay off my mortgage and put the rest into a mix of term deposits and ETFs, probably.
A combo of the above – I’d pay off enough of our mortgage to ditch the PMI. But we got the first-time buyers’ tax credit when we bought our condo, so we have to live there for another year and change (3 years from purchase) so we don’t have to repay it. Out of the rest, I think I’d put some cash in the bank for emergencies, then I’d buy either a single-family house with possibilities to convert a basement or something to a rental unit, or a fixer-upper two- or three-flat with the possibility of duplexing the first floor with the basement for us to live in, plus a rental unit or two. (And a yard! And a garage!) Some of the cash would also go to rehab the place. Being a landlord would be a lot less stressful if I knew that we wouldn’t be screwed if the tenant skipped out on rent, or if we had trouble renting it. Then, once we could sell the condo, we could live somewhere where we don’t have to live by committee.
Mortgage
Other debts
Buy new cars
Education for the kids.
I’d pay off my mortgage and use the remainder to buy a burger at Wendy’s, assuming I could find enough change in the ashtray.
I would invest in a small business.
I’d hope to find a way to invest it in a rental property, that I could turn into a full-time job with free housing. Maybe hire a property manager, and I could be their admin assistant.
Mortgage, then CDs.
I’d buy a mix of stock and bond index funds/ETFs, dollar cost averaged over the next year or so, depending on how fast Europe implodes.
If I had to invest it, it would be in term deposits. If I didn’t, I would pay off my house and car and then put the rest into term deposits.
Combination of the first three (although only about 25K in CDs), plus a big house to replace my condo which has such huge monthly fees that I’d be paying a lot less in property taxes, utilites, and repair than I currently am on mortgage and monthly fees.
I’d invest it in having/adopting a baby and being able to stay at home with it.
Half a million windfall? I would set aside half of it for my estate to supplement life insurance, etc then use the remainder to finance a* Leaving Las Vegas* type spectacular.
Either that or mutual funds.
I was going to answer this, but then I remembered I was in someone’s will for $500k. So now I feel bad about spending all that future money. :o
I would be sorely tempted to allocate 10% as fun money - go on a fantastic trip, and then improve the community workshop my hubby is involved in, and improve my studio. These could all be viewed as investments of sorts - the trip experience would be an investment in my art career 
We would move to a slightly larger house, and the rest would go in retirement savings (mutual funds primarily).
Like the old joke;
I would spend half on wine, women ,partying and vacations. The rest i would waste.
I spent the rest on a broken platinum coated calculator
At about 50 bucks each to get a cat fixed, I might be able to make a big difference in the overpopulation here with that sort of money. Hand it over, 50,000 male cats will lick their balls in your honor. The females might or might not know how lucky they are, depending on how old they are.
I went with rental property because you said you, not you and your spouse.
I am handicapped, and I could buy a decent rental property, perhaps a duplex where I could live in one side and rent out the other, and have a real estate agency manage the rental half [that way the tenant would not know that I owned both sides.]
If it were mrAru and I, we sort of would like to move back to California to be near his side of the family when my Mom passes, and switch over to farming [we were thinking breeding wagyu cattle for the high end meat market, no antibiotics or hormones, grass fed, and so on, with a bit of light produce on the side to sell at a farmers market locally.] which obviously I can’t do alone. We found 90 acres for $200K, restricted to ag use. We could actually set up with a bull and 4 heifers, a ram and 4 ewes [rambouillet] a boar and 4 sows and our current batch of poultry for about $400K leaving the last hundred K as working capital for the first couple years of expenses. [the property has a barn and is even fenced squee]
A mixture of govt bonds and stocks/bonds. It wouldn’t be enough to buy a one-bedroom flat where I live, I can’t move, and if I bought property elsewhere then I’d lose my own home (can’t rent Housing Association when you own a home). If courses and specialist software count as investments, then I’d go for that too.
We’ve talked about this. A significant amount of found money would be split in 4 equal parts - 1 part invested conservatively long term, probably a mix of government bonds and safeish stocks, 1 part pays off debt (that should cover all our debt except part of the first mortgage), 1 part philanthropic, 1 part fun & games, including travel, car upgrade, a few little toys. That last part would probably have $100K in short-term invested so we could spend it over several years with the first $25k kept out for immediate fun.