We have something like this at our firm (IT consulting shop). Every Christmas, everyone gets to propose & vote on projects (software and otherwise) that we should fund.
Oof, I'm afraid I don't know of any. Our company is generally very, let's say, employee-oriented and has been doing donations this way for a long time (longer than I've been there), so I don't know how our bosses came to like this approach.
One argument would certainly be: Employees / engineers tend to know much better which projects are worth supporting and/or in need of financial help.
