Genre, Categories, how about adding TROPES.

[Yousuke]

You know from TV Tropes.
'Categories' is sort of the same thing really, but not quite as accurate. And tropes are often spoilers, so it should be a hidden feature with a <show> button of some sorts.
Anyways.. would love that. Sort mangas by tropes I really like? How awesome would that be?? (eg. Magnificent Bastard, CrowningMomentOfAwesome etc.)