A lot of people are putting together office or workplace lottery pools. Multiple people chip in, many tickets get bought, and if any of them happen to contain the lucky numbers, everyone who joined gets a piece of the prize.
Now, this isn't for everyone. First of all, some people simply don't like gambling--and some even have a real problem with it. You don't want to encourage a bad habit among your employees or colleagues if you can help it.
Secondly, there's nothing wrong with being realistic about the odds. 1 in 303 million is, well...let's put it this way:
You're more likely by a factor of ten to get killed by a shark, bear, or vending machine than you are to pull down the winning Mega Millions numbers.
Despite all of that, participating in a pool can be pretty fun. A big part of that is the camaraderie. You win together, you lose together (spoiler alert: it's probably lose), and almost everyone likes having that sense of togetherness at work.
If you're planning on forming a pool, or are already part of one, you need to make sure of one thing:
Clearly document to set expectations.
If someone you work with is willing to pocket what's rightfully yours, you (or they) are probably at the wrong job to begin with. All the same, it happens. Make sure there's a clear record of who paid, and what the ticket numbers are (i.e., e-mail thread). That way people can't jump in after the fact, or use the "I bought more tickets so I get more money" attempt.
BUT ... if you're confident you and your co-workers can all get along, then it's not too late to go out and buy a batch of tickets. There's another $620 million up for grabs in Wednesday's Powerball drawing, as well.