Simple Registration

I would like to run a promotion to get people to join our community, but want to make the registration process (just for this activity) as simple as possible.

How can I create a registration page (or module) that allows people to just enter their first name, last name and email address and then have a user password sent to them (user=email?)?

I do not want to affect the standard registration process, but have this as an additional one.

If you're using CBSubs you could have a plan that hides various fields on the Workflows tab of your plan. Otherwise you could use CB Conditional with a profile type field for them to select a simple profile or something of the sort. Aside from that you can't really do this with CB as we don't have multiple separate registration forms. You'd need to develop something that utilizes CB API to register them with only your simple inputs.

I have used the CBSubs option, but cannot work out a way to show a password, which I assume is not created.

Not having a password makes the user experience poor, unless there are any interesting short cuts.

I don't recommend hiding the password. Let them supply at the very least the basic core fields such as name, username, email, and password. Everything else is basically optional for Joomla so they can function without everything else. You could however turn off the password fields display on registration so it'll generate a password during registration, which they can change in profile edit if they wanted, but this affects all users.