I would at least hedge against inflation. Silver has a bigger upside than gold, and silver should be higher than 26-27$ come April. Again, it isn't riskless, but it is about as riskless as one can be while also hedging inflation (and possibly getting a net return over the rate of inflation). Your choice though. (Agricultural & other commodity stocks would probably be a decent investment for 6 months time)
Though, if you must have the 10,000 on April 15 (I assume you mean you will be owing Gubbermint taxes), I wouldn't spend it at all, unless you want to do some Civ Dis and not pay the taxes whatsoever. Certainly an option there.