So, here's two friendly reminders about how to be awesome at making announcements, on Facebook or "in real life".
Communicate value, not events
What's way better is to stop trying to communicate what is happening, and instead to communicate why you should care. If I want to help people to come to Ancon, I shouldn't say, "Rego closes in two weeks!" - which only plays on people's fear of missing out. I would be better off saying, "Ancon is all about having your life changed by Christ," and then lead into how to register.
If an event is about helping people to love food, then talk about how amazing the food is going to be. But if it's just an excuse to hang out and get to know people better, then make sure you talk about building friendships and spending time with others more than you talk about food. And if your event is really about hearing a talk, or about connecting with nonbelievers, then make sure that's what you communicate!
Make it really easy to respond
Don't make people look something up when you can provide them with a link they can click on. Instead of asking for an email, consider taking responses in the comments thread. Rather than asking people to choose between 10 different options, see if you can reduce the number of choices they need to make. And try not to ask people to do more than one thing at a time!
I had other ideas about tips like how to motivate people well (don't use fear and guilt) and considering who needs what information (don't use a big forum to talk to a little group of people), but you can ask me about those if you're actually interested :P