I created a new jQuery pluging that works with the new Facebook javascript SDK to present a users list of friends and allows them to select the friends they would like to do X with. That “X” is up to you; once the user has selected their friends, you call a function on the plugin that returns an array of the friends Facebook Ids. A few key points:
client-side, no server-side PHP blah blah blah dependencies like some of the other alternative friends selectors
depends on jQuery and the new Facebook Javascript API