Flickr: Multi Group Sender
UPDATED Septemberl 2014
Multi Group Sender adds a new button titled "MGS" above your photos, clicking it activates the multi group sending function.
The script is now compatible with Firefox, Chrome, Safari and Opera.
Remember the script is donationware, that means if you like the script please make a donation.
Get the updated script here: steeev.site50.net/flickr/multi.group.sender.htm
This script and all my other Flickr scripts are available here: steeev.freehostia.com/flickr