Hi Vincent!
XBMC now allows you to add "Tags" Here is the link to the announcement, you may have to go down the page a little)
http://xbmc.org/xbmc-11-0-july-cycle/
Here is the quote
[Google Summer of… Database Improvement – Tags
The work being done by devs JMarshall and Montellese as sponsored by GSoC has resulted in a stream of new updates and features this month. In particular, because scraped moviesets are intentionally limited to one per movie for clarity by TheMovieDb, movies (and potentially other media in the future) can now be tagged with additional info by the user with Tags. Think of Tags as personal moviesets that the user can create in the XBMC interface. At the moment, tags are limited to movies, but can be extended to tv shows and music videos in the future. Below is a quick video of how Tags work.]
This threat explains it really well[/quote]
http://forum.xbmc.org/showthread.php?tid=138498
The beauty of Tags is that one Movie can have several Tags.
For example, - "Avatar" can have a "3D Movies" tag as well as a "German" tag. If you do that in sets in can only be in one set.
Tags work great within XBMC just not as visual and pretty as XBNE is.
Hope this makes sense!
Thanks once again and God bless
Alfred