I am trying to customize registration for a site my department is building. We want the registration process to consist of gathering a username, email address and password. For privacy reasons, we don't want to collect user names.

I have tried a module that allows some limited customization of the registration process (you can specify which fields to include, so can remove the first and last names), but have encountered some problems with it.  This registration happens in the same module which does login. If you click on the Register link on the top right (in the default layout), it still takes you to the default registration page which requires all the usual fields to be entered.

But if you change the registration page in Site Settings to go to the new registration/login page, then something else breaks. After you've logged in, where clicking on your displayname in the top right would normally take you to edit your profile, now it takes you to the page with the custom login/registration control (which hides itself since you're already logged in). So, users can no longer modify their details.

As far as I can tell, DNN lets you specify other fields in the profile to be filled in during registration, and even to define new registration fields, but has no way of removing first and last name from the required fields (even if you tell it, in the User Accounts/Manage Profile Properties page, that the first and last names are not required and not visible).

In general, is there any way to modify DNN's registration page without writing a complete replacement for it? (apart from the ability to add new fields)  DNN doesn't appear to supply any way to edit the registration page directly, say if you wanted to modify any of the text on it - though I expect there are good reasons for that.

I would be delighted if there's a commercial module that does this painlessly.

I htink our module SimpleSignin could do that. It also allows you to create custom contact forms.