This Ginevra "Ginny" Weasley fan art contains
cocktail dress and sheath.
There might also be
dinner dress, dinner gown, formal, evening gown, strapless, bare shoulders, and bustier.
The first TV spot for Harry Potter and the Half-Blood Prince. Same footage of Ginny, except for her by Ron's bedside. But, I still couldn't help sqeeing like crazy.