If you want to create an event that will unite your employees and raise a lot of money, consider doing one big fundraising drive across your locations. This is a really great way to raise money if you are short on resources and don't have a staff to run monthly or quarterly fundraising events.
The idea is to choose 1 day out of the year and designate it as your company's "giving day". You can select a special date, for example the anniversary of your company's founding. Or your founder's birthday. Whatever date you choose, before you announce any plans, be sure to partner with your Finance department to ensure that you have the proper processes in place to support a program on this grand a scale. It's important that you establish this up front because you never want to launch a campaign of this magnitude without the proper "checks and balances" in place form a finance and audit perspective. Once you have all your financial "ducks in a row", partner with your Marketing and Communications department to promote the heck out of it. You'll want to highlight the reason why you are doing this fundraiser, and which non-profits will be the beneficiaries of your giving. Be sure to tie it back to your company's culture and values. Create posters and a communications campaign around the event to keep employees informed and engaged before, during, and after the event. Post information about the fundraiser on your company's intranet with a countdown to the big day. Provide regular status updates on funds raised. If you have it in your budget, have shirts or pins made up that you can distribute to all your employees in commemoration of the event.
You can set a fundraising goal, or you can make it a fun "competition" between departments, divisions, or locations. It's a super way to engage your employees and raise money for our deserving non-profits.