Event scheduling and RSVP tracking.
2 Dec 2013: I'm using the latest version of WP and the latest version of the plugin to manage the RSVPs of a 20-person event because some of the people are still not on Facebook (my preferred method for events these days). There is a small glitch that I've already reported on the events compilation page, but the plugin is otherwise very easy to install and use. I organize events regularly so this, along with its spreadsheet exporting function, are a real win. Just what I needed!
Many thanks, Mr. Developer!