Browsing through an aviation magazine, I chanced upon a term I hadn't heard of before, spiroid winglets. Typed in google and got this cool shiite:
Click on the pictures, the tips are actually looped surfaces.
Anyway, I was always curious why the intersection of endplates and wing is always consistently an abrupt perpendicular abutting of two surfaces, instead of something with smoother contours. I suppose it maximizes surface area of the wing, but it seems like it might be an area that teams could exploit for drag reduction.