Meetup.com decided to crank up the API rate-limiting. Essentially, they throttle pretty quickly now if you make very many consecutive API calls at all in succession. In case you don't know, our website basically simply displays info from Meetup.com via these APIs.
When I get some time soon I'll be updating the site to use some of their newer APIs that apparently return more of the data in fewer requests. If anybody else has time before I get to it (hopefully this week?) let me know and maybe I can help get you started with helping.