The only anime that comes to mind that's like fate stay night and sekirei is Kurokami.
As for negima I'd say possibly To Aru Majutsu no Index (in both have sorta harem like genre plus the whole supernatural power thing). although then again To Aru Majutsu no Index is also slightly similar to Zatch Bell (lets just say that memory lost thing Zatch had also occurs in To Aru Majutsu no Index as well).