In a walk around the local park, a pair of Great Tits called my attention. They were calling and foraging in a horse chestnut. I watched how dexterously they grabbed the large leaves with their bills, pulled them towards them, and held them with one foot while feeding (top shot). They were looking for larvae or pupae of the horse chestnut leaf miner, Cameraria ohridella, a micromoth that has expanded its range throughout Europe from its native Balkans. The moth's larvae feed inside the leaves of the horse chestnut, leaving them speckled. Blue tits also feed on this leaf-miner (as do Marsh Tits), and I've seen them feeding on them before, but as they are lighter than Great Tits, they are able to just hang from the leaves themselves.
This is a short clip documenting this behaviour.