Donate to the FSF via the United Way
Just how do to this depends on where you live, because the United Way is not a single nationwide corporation but a loose alliance of separate local organizations with distinct bylaws and methods. Some United Way chapters list the FSF as an affiliated charitable organization, which is a pre-approved recipient of donations. Some will approve any 501(c)3 organization, which includes the FSF. Some have a narrow, explicit focus, but may be willing to consider including the FSF, if you ask. Some chapters use a form that prompts for an unlisted "other" recipient and others require more initiative from you.