I came across several of these tiny moths dancing around an oak leaf. They seemed to be competing with each other to occupy the high points at the edge of the leaf. They are probably Micropterix aruncella (Lepidoptera: Micropterigidae).
The colour or these small, metallic-winged moths seems to depend upon the level and angle of lighting, which is why I have included three photos here.
Photos taken in Whiteknights Park, Reading University grounds, Reading, Uk, on 2010-05-21.