You go over to O'Reilly and buy a DRM-free e-book. Now, the FSF likely won't suggest that because they don't like mentioning the existence of “non-free” documentation, but IMO one of the best ways to protest DRM is by saying, with our pocketbooks, that we want e-books and are willing to pay good money for them but find DRM unacceptable.

If Tor had gotten their DRM-free book thing in order by now, rather than waiting until July or so, I'd probably also be buying a Tor e-book today.