A nice replacement for userreference widget would be welcome. Something along the lines of facebooks multiple user selector as in messaging and some other places. It would be perfect for user reference fields, privatemessages, user relationships, OG invites, rsvp and multitude of other existing modules. I think best way would be creating multiple (friends, fellow og members or any other kind of user) default user views that returns user picture and name (or any other field) and jquery magic on returned html and thats it...
I got very close to this by making view for use with userreference fields, got nice user list with checkbox besides each user, it was just too long list since there can be hundreds of users that view returns. I wanted them to be in div with overflow hidden and some search box/first letter selector to quickly find user as well as some tab or dropdown select to choose particular view that returns list (like friends or fellow og members).