Hi All: Is there any open source project that can be used to build a on-line ticket sales system, like: ticketmaster or eventbrite etc..? Thanks!

CiviCRM with CiviEvent

http://freeseat.sourceforge.net/

Drupal with a combination of modules like Signup, Event, Ubercart, and UberCart Signup

Try searching Google for open source ticket sales software

none: Charles Robertson | none