First of all, I just wanted to say... this is a nice simple plugin that serves its purpose well. Thank you for taking the time to develop it, and for making it freely available to us all!
I do have one request that I would like to see added in a future version if possible though. When you use the [username] shortcode in the welcome text, it makes the username a hyperlink to the user's profile page. I would like an option to remove that hyperlink and have it displayed as plain text instead.
For now, I've achieved this by editing line 72 in login-logout.php to read:
$username_link = $username;
That is all. Thanks again and keep up the good work! :)