Barcodes would really be great. It would make a huge difference at check in time when you've got several hundred registrants.
Each time I have to put together a ticket or registration site, I look longingly at Fusionticket which does barcodes automatically, but it's not a joomla component, perpetually in beta and tech support is non-existent.
Fusionticket is php and open source, so perhaps someone can find a way to integrate the appropriate pieces into DTregister?