Multiple file upload via HTML5
I got tired of waiting for Meetup to do this, so I did it myself via a userscript (installable on Google Chrome or Greasemonkey/Scriptish for Firefox): Meetup: HTML5 multiple-file upload for photos for Greasemonkey - http://userscripts.org/scripts/show/111278
If you want to upload multiple files via HTML5, Meetup.com currently offers 2 methods:
1. Upload via Adobe Flash applet. Extremely unreliable, crashes frequently for many people
2. Convention HTML form-based upload, with which you must select files to upload individually. This takes a *long* time and much manual work.
There should be a 3rd option: HTML5 multiple file-upload. HTML5 introduces the "multiple" attribute that allows selecting & uploading files through 1 widget, done through any modern web browser (MSIE9, Chrome, Safari, Firefox, Opera, etc) all of whom are more responsive to browser/plugin crashes.