Neil,
I noticed that when I use the popup message (which I think is awesome) I do not have the option to customize the subject. The popup apparently pulls the subject line from the name of the page for that instance of the module.
It would really be nice to have either a custom subject set up by the admin or a blank subject that can be filled in by the person submitting the email to a friend.
One last thing...on either popup and simple/simple+ would it be possible to just have a "send" or "submit" button?
Terry
Oh...one last future upgrade suggestion...On another website I frequent they track how many suggestions/invitations a given user has sent and their subscription is automatically extended for six months every time five people join the site. I'm not sure how this is implemented but it is a great option to motivate users to invite others.