Here is the light novel sales ranking for March 2nd - 8th.

*1, Toradora!vol.10
*2, To Aru Majutsu no Index vol.17
*3, Rental Magica vol.16
*4, Meg and Seron vol.4
*5, Mobile Suit Gundam 00 Second Season vol.1
*6, Code Geass - Hangyaku no Lelouch Novels R2 vol.4
*7, Kaze no Oukoku Suna no Meikyuu
*8, Rinkan no Madoushi vol.4
*9, The Sky Crawlers vol.6 Sky Eclipse
10, Koi no Yokan wa Amaku Kaoru

11, Miwakuteki na Kiss no Mahou
12, Zero no Tsukaima vol.16 *third week
13, Durarara!! vol.5
14, Mikohime-sama to Shirobara no Mitsuyaku
15, C3 vol.6

Additional info:
Durarara!! is a light novel written by Narita Ryohgo, the author of "Baccano!". Aniplex has acquired a domain "drrr.jp" last November, indicating a future announcement of the anime.

Source: Kinokuniya