This has probably been thought of, but I just "discovered" it and thought I'd share.
I enjoy drawing a lot of eye(s) - both animal and human. Lashes are time consuming. With the new Feather style I set up new layer, draw feather line along eye lid (sometimes 2-3 times depending on depth wanted) then I erase the opposite edge. Perfect lashes in seconds. Can use colors for "mascara".