You can already hide your "friend-of" list on LiveJournal; why can't you hide your "friends" list? This patch provides that functionality.
Why is this useful? Well, suppose I have a friend with a private journal that she'd prefer other people not find out about. I'd still like to read her in my friends view, but I don't want her journal name appearing in my friends list.
(Note that this does not alter her view at all. She can still see me listing her as a friend on her userinfo page.)
Of course, this leaves unaddressed the issue of someone simply looking at my friends page and seeing posts by this "secret" friend. This can be worked around by editing my "Default View" friends group, I suppose, and that's what I plan to do-- offhand, I can't think of a better solution that could be designed.
If you'd like to see the patch in action, it's running on my goathack:
Test is a normal LiveJournal user, who lists (and is listed back) by himself and by user "evan".
Evan, on the other hand, has enabled the "hide friends list" functionality, so in his userinfo you cannot see his friends list.
To use this patch, apply it, then
cd bin/upgrading/ ./update-db.pl --populate
(this adds the extra userprop to the database).
The patch is available at http://goathack.livejournal.org:8012/patches/hidefriends.patch.
I include the full text of it here, too, for history purposes (I guess).
Never mind, it screwed up the formatting of this post.