Authenticate joomla users to drupal website I know this is not 100% drupal question but It might be the case that someone has StumbleUpon this one before. 

I would like to give the opportunity for people having an account on a Joomla website to login to mysite and create a very basic account(automatically) when doing that.
Something similar to facebookconnect.

Has anyone done this before?

One solution could be to use the connect module and find a way to expose the needed info on the joomla website.
I'm not sure on a module based solution, but i would just add a custom form submit function on the user_register_form and then code from there. Success would depend on how you can remotely authenticate with Joomla.