I tag her as わ島花音 on last.fm.
If they go by their name, I just use the kanji cuz Kanon Wakeshima irritates me cuz I'd rather romanize it as kan'on, but then wakeshima kan'on looks wrong to me too...so I use the kanji.
But, if I'm saying her name aloud or talking about her, I'll just Kan'on Wakeshima or Kan'on. XD