fferraiu

This plugin allows you to integrate your wordpress blog with the platform capabilities of meetup. 
This provides a widget that allows you to view a list of recent activities of your group meetup.

MeetupUserActivityWidget

Allows you to integrate your wordpress blog with the platform capabilities of meetup

Kelly Choyce-Dwan

For use with a <a href="http://meetup.com" rel="nofollow ugc">Meetup.com</a> group.
This plugin creates two widgets: one a list of events from a meetup group (by ID or URL name, for multiple groups use IDs); the other shows details about single event (by ID) with a link to RSVP – using OAuth if keys are specified, otherwise just a link to the event on meetup.com. Does require at least an API key (which it asks for on the settings page).

Meetup Widgets

Adds widgets displaying information from a meetup.com group.

MeetupUserActivityWidget vs Meetup Widgets