Where do you park money in the short term?

For those who have built up some capital, when you're buying and selling properties / notes / whatever and there's $$ laying around that you intend to put to work later, where are you holding it? The problem I'm seeing is the next project could come in 1 month or 12 months. I don't want capital doing nothing for 12 months, but I've already once made the mistake of locking it up for too long (not available when I need it). Options I've dabbled in include crowd funding platforms, municipal bonds, and plain old bank account.