Back in the day, before we could choose an admin user name and password, WordPress automatically generated a random password for the user "admin".
How about leveraging that functionality to generate a random password for new user creation?
I've found time and time again, when adding new users I have to generate a random string to add their account. A simple "generate password" button on the Add New User page should do the trick.
Granted there are many single user installs, but I think there are also a fair amount of multi-user installs that this could help improve the experience on. Not to mention it should be very simple to implement.