Display a textfield other than username throughout site

Hi,

I'd like to display a field other than a member's username throughout the site. With the ability to login with email addresses, the username doesn't seem to have much use past in the URL, and is limited( no spaces, etc). I'd think if I just change the display from username to field xyz, but keep the underlying links, it shouldn't be an issue.

I'm having trouble finding where the username is past onto the page, however. If I change this in BxSoundsSearch.php for example, it comes up blank:

'ownerName' => 'NickName',

Thanks,

Alan