How can I replace this one aspect of Facebook?

I am quitting Facebook at the end of October, giving people I know adequate notice of other methods to keep in touch with me. Most of the things I use FB for are easily replaced with other things; twitter for status updates and links, flickr for my photos, pinterest for other pics and stuff that’s interesting. There’s just one thing missing.

I was on the verge of setting up a FB group with a friend, for the purpose of organising social events for a group of mutual friends in my local area. I’d still like to do this somehow and ideally without requiring anyone to have to sign up for a new service (like Meetup for example). The only thing I can think of is just to collect all of their email addresses and send out an email once a month. But is there a friendlier alternative?