I've only discovered the project duo kanon×kanon a few days ago and I must say I'm really hooked on their music.
kanon×kanon Is a project duo formed in 2010 by cellist and vocalist Kanon Wakeshima (分島花音) Kanon and from the popular oshare kei band An Cafe (アンティック-珈琲店-). Their first single is called Calendula Requiem (カレンデュラ レクイエム) and it's also the second opening theme from the anime Shiki.
Their single of the same name contains two other songs. A download link can be found below.
kanon×kanon - Calendula Requiem
01. カレンデュラ レクイエム (Calendula Requiem)
02. ザ ドールハウス! (The Doll House!)
03. ウミガメスープ (Umigame Soup)
(this is not uploaded by me)