The site I'm currently working on and discussions I've had with friends, a few have asked me to build exactly what you've got.
Others didn't want me to abandon the original idea, so I'm sticking to my guns, figuring somebody would nail the space you're going after (plancast is trying, but haven't seemed to capture the ad-hoc-iness that you've got).
I like your nice clean design and the simplicity of adding events, though I didn't get any sort of pop-up to post to my facebook page, so I can't really inform my friends about it (I used one of my old fb test accounts).
I see you linked in to your cirque list, which I think is really great, to get intros to other people who are looking to do similar things.
I'm going to be in Vancouver in the next week (I'm from Whistler) let me know if you want to meet-up for coffee and I can tell you about the suggestions I've had from my friends and my thoughts related to your project.
I can be reached at pete / hearwhere.com