The New York History Blog is updated several times daily, so it provides a very frequent and widely read venue for notifications. I recommend that organizations use The New York History Blog to make announcements and promote themselves. You can write an essay about what you are doing and how it relates to history in New York State, or submit press releases about your news and events (learn how to submit here).
I recently wrote about some events that I think are outside the ordinary. You can read about them here.