The official website has a whole heap of good material, including a donation page, the link to their campaign for men to swear an oath never to commit, never to excuse, and never to remain silent about violence against women. Crucially, there is also a link for where to seek help.
Previous HAT posts about White Ribbon Day and the campaign to end violence against women:
Addendum Dec 5th: I just saw this powerful video from Amnesty International with Patrick Stewart talking about growing up with domestic violence from his father against his mother. So very, very powerful.