This post is a request into the aether for something I'd really like to see and would be willing to pay for. My hope is that someone reads this and decides to build it (maybe even Meetup). I unfortunately don't have the time to build this as much as I'd like to do so.
Background
Meetup is great. I've been using it since December 2004 when I had my first PHP Meetup and we're still using it for Madison PHP. I've seen it struggle under the weight of free spammy groups and I was thrilled with it's decision to drop free groups altogether. However over the last couple years it's become clear to me that Meetup and I have different views on the future. Recently Meetup stopped supporting custom domains, opting instead to redirect my domain to my group.
This is just one small thing but it illustrates the direction Meetup is going. It wants to be a silo like Facebook or Twitter. Obviously they want to reinforce their brand and they want to make it harder for people to leave their platform but that's exactly why I'm now thinking about leaving. I don't like the idea of my group being held hostage. They clearly want the dynamic to be "I have a Meetup Group" and not "I have a group that uses Meetup".
Alternative
So, what would I like to see?
I'd like Meetup to take a WordPress model. Release open source software that would allow anyone to run their own meetup on their own website for free.
It would support plugins so group leaders could choose different e-mail back ends like MailChimp or AWeber. People could extend it for things like job boards or embedding slides or video to events. You could create a plugin to integrate your site with other sites like joind.in.
It would support themes so you could really customize it for your particular group.
Meetup.com would still exist as a service provider. They could charge for things like having a fully hosted meetup group (just like now) as well as services like e-mail delivery and a marketplace for premium themes and plugins.
One other service that I think would be fantastic is the ability to pay to have your self-hosted site listed in the meetup directory. This would mean that going to meetup.com and looking for groups in your area would still be high quality. It could require a strict approval process to keep the quality high. The administrative costs would be covered by the fee.
I'd really like to see Meetup run with this. I think it's a great service and I think it would make them far more profitable in the long run. But like I said earlier, I don't think my vision is what Meetup has in mind.