There are some three month CD's floating around. Not the greatest return in the world, but still a little better than 2.93%. Pretty much anything else will cost you more in fees and withdrawal penalties (or taxes) than it will return.
2.93% will get you a three-month return of around $5000 on a 700k investment. IIRC the three month CDs were coming in at around 4.1%. That's a $7000 return for the same period.
If you don't absolutely have to have the money in three months, I would be tempted to pick up some rental property that will return at least 12% per year (1% per month). If you see and average amount spent for repairs, maintenance, taxes, and insurance, you should still net at least 8-9% cash on the investment, plus the any equity gain from market appreciation. However, this is a long-term strategy.
Or you could buy $700K worth of gold (about 110 lbs) and put it in a large safety deposit box .
Sure would be pretty to look at, but gold and precious metals are really not a good option due to the volatility of the market (unless you like taking that kind of risk). That, and metals are really high right now (compared to three or four years ago). Plus, when you go to sell, the people normally set up to buy that much gold are usually metals dealers and they will want to buy at significantly under market value. If the price of gold remains unchanged, that's a built-in loss on investment. Yuck.
Some will try to get you into some day trading, but I wouldn't recommend that unless you have a LOT of market savvy.
What will the money eventually be doing? Maybe there is a good investment strategy that will get you closer to your eventual goal.
Brad