Email as a username

Easy to do! Steps:
1) Copy /components/com_jlinked/views/loginregister/tmpl/default.php to /templates/<YOUR_TEMPLATE>/html/com_jlinked/loginregister/default.php
(Create the directories that need to be created)
2) Edit that new file.
3) Around line 36, you'll see a div like:Delete that block down to about line 60 (the closing div).
4) On the next div, increase the width from 45% to something like 95% so it takes up the whole width.

Modify however else you need

Let us know how that goes!
Alex