Why not linking on this site?
Just create an UI-overview on your site with previewpicture, UI-informations like author and maybe even usercomments while the downloadbutton leads on this site, mabye called "Download from LOTRO-Interface".
There's no real downside, if you choose this method. There are even benefits for you:
- You won't have to update the UIs on your own, when an author release a new update
- You'll never have problems with the copyright
- You won't use your own webspace and traffic
But keep in mind, that you shouldn't link on the files directly. The Link should always lead to downloadpage of the UI.